Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: ATPase.
Artykuły w czasopismach na temat „ATPase”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych artykułów w czasopismach naukowych na temat „ATPase”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj artykuły w czasopismach z różnych dziedzin i twórz odpowiednie bibliografie.
1
Martins, Samantha M., Christiane R. Torres i Sérgio T. Ferreira. "Inhibition of the Ecto-ATPdiphosphohydrolase of Schistosoma mansoni by Thapsigargin". Bioscience Reports 20, nr 5 (1.10.2000): 369–81. http://dx.doi.org/10.1023/a:1010330017583.
Pełny tekst źródłaStreszczenie:
ATPdiphosphohydrolases (ATPDases) are ubiquitous enzymes capable ofhydrolyzing nucleoside di- and triphosphates. Although a number ofpossible physiological roles have been proposed for ATPDases, detailedstudies on structure-function relationships have generally been hamperedby the lack of specific inhibitors of these enzymes. We have previouslycharacterized a Ca2+-activated ATPDase on the external surface ofthe tegument of Schistosoma mansoni, the etiologic agent of humanschistosomiasis. In the present work, we have examined the effectsof thapsigargin, a sesquiterpene lactone known as a high affinityinhibitor of sarco-endoplasmic reticulum calcium transport (SERCA)ATPase, on ATPDase activity. Whereas other lactones tested had littleor no inhibitory action, thapsigargin inhibited ATP hydrolysis by the ATPDase (Ki∼20 μM). Interestingly, hydrolysis of ADP was notinhibited by thapsigargin. The lack of inhibition of ATPase activityby orthovanadate, a specific inhibitor of P-type ATPases, and theinhibition of the Mg2+-stimulated ATP hydrolysis by thapsigarginruled out the possibility that the observed inhibition of the ATPDaseby thapsigargin could be due to the presence of contaminating SERCAATPases in our preparation. Kinetic analysis indicated that a singleactive site in the ATPDase is responsible for hydrolysis of both ATPand ADP. Thapsigargin caused changes in both Vmax and Km for ATP, indicating a mixed type of inhibition. Inhibition by thapsigarginwas little or not affected by changes in free Ca2+ or Mg2+concentrations. These results suggest that interaction of thapsigarginwith the S. mansoni ATPDase prevents binding of ATP or its hydrolysisat the active site, while ADP can still undergo catalysis.
2
Zhao, Dayuan, i Naranjan S. Dhalla. "Influence of gramicidin S on cardiac membrane Ca2+/Mg2+ ATPase activities and contractile force development". Canadian Journal of Physiology and Pharmacology 67, nr 6 (1.06.1989): 546–52. http://dx.doi.org/10.1139/y89-088.
Pełny tekst źródłaStreszczenie:
The effects of gramicidin S (GS), an antibiotic, on the rat heart membrane ATPases and contractile activity of the right ventricle strips were investigated. GS inhibited sarcolemmal Ca2+-stimulated ATPase (IC50 = 3 μM), Ca2+/Mg2+ ATPase which is activated by millimolar Ca2+ or Mg2+ (IC50 = 3.4 μM), and sarcoplasmic reticulum Ca2+-stimulated ATPase (IC50 = 6 μM). The type of inhibition for the sarcolemmal Ca2+/Mg2+ ATPase by GS was apparently uncompetitive, while that for Ca2+-stimulated ATPases in sarcolemma or sarcoplasmic reticulum was of mixed type. Other ATPases, including mitochondrial ATPase, sarcolemmal Na+–K+ ATPase, and myofibrillar ATPase, were not inhibited by this agent. GS also decreased the rat right ventricle maximum force development (half-maximal inhibitory concentration was 2–4 μM), maximum velocity of contraction, and maximum velocity of relaxation. The resting tension was increased by GS to over 200%. The contractile actions of GS were mostly irreversible upon washing the muscle 3 times over a 10-min period. Decreased Ca2+, Mg2+, Na+, K+ concentrations in the perfusate increased the effects of GS. These findings showed that GS was a potent inhibitor of divalent cation ATPases of heart sarcolemma and sarcoplasmic reticulum and it is suggested that these membrane effects may explain the cardiodepressant action of this agent.Key words: gramicidin S, rat heart sarcolemma, rat heart sarcoplasmic reticulum, Ca2+/Mg2+ ATPase, Ca2+-stimulated ATPase, rat heart contraction.
3
Rawson, Shaun, Michael A. Harrison i Stephen P. Muench. "Rotating with the brakes on and other unresolved features of the vacuolar ATPase". Biochemical Society Transactions 44, nr 3 (9.06.2016): 851–55. http://dx.doi.org/10.1042/bst20160043.
Pełny tekst źródłaStreszczenie:
The rotary ATPase family comprises the ATP synthase (F-ATPase), vacuolar ATPase (V-ATPase) and archaeal ATPase (A-ATPase). These either predominantly utilize a proton gradient for ATP synthesis or use ATP to produce a proton gradient, driving secondary transport and acidifying organelles. With advances in EM has come a significant increase in our understanding of the rotary ATPase family. Following the sub nm resolution reconstructions of both the F- and V-ATPases, the secondary structure organization of the elusive subunit a has now been resolved, revealing a novel helical arrangement. Despite these significant developments in our understanding of the rotary ATPases, there are still a number of unresolved questions about the mechanism, regulation and overall architecture, which this mini-review aims to highlight and discuss.
4
Russell, V. E., U. Klein, M. Reuveni, D. D. Spaeth, M. G. Wolfersberger i W. R. Harvey. "Antibodies to mammalian and plant V-ATPases cross react with the V-ATPase of insect cation-transporting plasma membranes". Journal of Experimental Biology 166, nr 1 (1.05.1992): 131–43. http://dx.doi.org/10.1242/jeb.166.1.131.
Pełny tekst źródłaStreszczenie:
In immunobiochemical blots, polyclonal antibodies against subunits of plant and mammalian vacuolar-type ATPases (V-ATPases) cross-react strongly with corresponding subunits of larval Manduca sexta midgut plasma membrane V-ATPase. Thus, rabbit antiserum against Kalanchoe daigremontiana tonoplast V-ATPase holoenzyme cross-reacts with the 67, 56, 40, 28 and 20 kDa subunits of midgut V-ATPase separated by SDS-PAGE. Antisera against bovine chromaffin granule 72 and 39 kDa V-ATPase subunits cross-react with the corresponding 67 and 43 kDa subunits of midgut V-ATPase. Antisera against the 57 kDa subunit of both beet root and oat root V-ATPase cross-react strongly with the midgut 56 kDa V-ATPase subunit. In immunocytochemical light micrographs, antiserum against the beet root 57 kDa V-ATPase subunit labels the goblet cell apical membrane of both posterior and anterior midgut in freeze-substituted and fixed sections. The plant antiserum also labels the apical brush-border plasma membrane of Malpighian tubules. The ability of antibodies against plant V-ATPase to label these insect membranes suggests a high sequence homology between V-ATPases from plants and insects. Both of the antibody-labelled insect membranes transport K+ and both membranes possess F1-like particles, portasomes, on their cytoplasmic surfaces. This immunolabelling by xenic V-ATPase antisera of two insect cation-transporting membranes suggests that the portasomes on these membranes may be V-ATPase particles, similar to those reported on V-ATPase-containing vacuolar membranes from various sources.
5
Tadini-Buoninsegni, Francesco, Stine A. Mikkelsen, Louise S. Mogensen, Robert S. Molday i Jens Peter Andersen. "Phosphatidylserine flipping by the P4-ATPase ATP8A2 is electrogenic". Proceedings of the National Academy of Sciences 116, nr 33 (1.08.2019): 16332–37. http://dx.doi.org/10.1073/pnas.1910211116.
Pełny tekst źródłaStreszczenie:
Phospholipid flippases (P4-ATPases) utilize ATP to translocate specific phospholipids from the exoplasmic leaflet to the cytoplasmic leaflet of biological membranes, thus generating and maintaining transmembrane lipid asymmetry essential for a variety of cellular processes. P4-ATPases belong to the P-type ATPase protein family, which also encompasses the ion transporting P2-ATPases: Ca2+-ATPase, Na+,K+-ATPase, and H+,K+-ATPase. In comparison with the P2-ATPases, understanding of P4-ATPases is still very limited. The electrogenicity of P4-ATPases has not been explored, and it is not known whether lipid transfer between membrane bilayer leaflets can lead to displacement of charge across the membrane. A related question is whether P4-ATPases countertransport ions or other substrates in the opposite direction, similar to the P2-ATPases. Using an electrophysiological method based on solid supported membranes, we observed the generation of a transient electrical current by the mammalian P4-ATPase ATP8A2 in the presence of ATP and the negatively charged lipid substrate phosphatidylserine, whereas only a diminutive current was generated with the lipid substrate phosphatidylethanolamine, which carries no or little charge under the conditions of the measurement. The current transient seen with phosphatidylserine was abolished by the mutation E198Q, which blocks dephosphorylation. Likewise, mutation I364M, which causes the neurological disorder cerebellar ataxia, mental retardation, and disequilibrium (CAMRQ) syndrome, strongly interfered with the electrogenic lipid translocation. It is concluded that the electrogenicity is associated with a step in the ATPase reaction cycle directly involved in translocation of the lipid. These measurements also showed that no charged substrate is being countertransported, thereby distinguishing the P4-ATPase from P2-ATPases.
6
Parra, Karlett J., Chun-Yuan Chan i Jun Chen. "Saccharomyces cerevisiae Vacuolar H+-ATPase Regulation by Disassembly and Reassembly: One Structure and Multiple Signals". Eukaryotic Cell 13, nr 6 (4.04.2014): 706–14. http://dx.doi.org/10.1128/ec.00050-14.
Pełny tekst źródłaStreszczenie:
ABSTRACTVacuolar H+-ATPases (V-ATPases) are highly conserved ATP-driven proton pumps responsible for acidification of intracellular compartments. V-ATPase proton transport energizes secondary transport systems and is essential for lysosomal/vacuolar and endosomal functions. These dynamic molecular motors are composed of multiple subunits regulated in part by reversible disassembly, which reversibly inactivates them. Reversible disassembly is intertwined with glycolysis, the RAS/cyclic AMP (cAMP)/protein kinase A (PKA) pathway, and phosphoinositides, but the mechanisms involved are elusive. The atomic- and pseudo-atomic-resolution structures of the V-ATPases are shedding light on the molecular dynamics that regulate V-ATPase assembly. Although all eukaryotic V-ATPases may be built with an inherent capacity to reversibly disassemble, not all do so. V-ATPase subunit isoforms and their interactions with membrane lipids and a V-ATPase-exclusive chaperone influence V-ATPase assembly. This minireview reports on the mechanisms governing reversible disassembly in the yeastSaccharomyces cerevisiae, keeping in perspective our present understanding of the V-ATPase architecture and its alignment with the cellular processes and signals involved.
7
Dane, Michaela, Kerstin Steinert, Kordula Esser, Susanne Bickel-Sandkötter i Francisco Rodriguez-Valera. "Properties Of The Plasma Membrane Atpases Of The Halophilic Archaebacteria Haloferax Mediterranei And Haloferax Volcanii". Zeitschrift für Naturforschung C 47, nr 11-12 (1.12.1992): 835–44. http://dx.doi.org/10.1515/znc-1992-11-1209.
Pełny tekst źródłaStreszczenie:
Both, Haloferax mediterranei and Haloferax volcanii membranes contain ATPases which are capable of hydrolyzing ATP in presence of Mg2+ or Mn2+. The ATPases require high concentrations of NaCl, a pH value of 9, and high temperatures up to 60 °C. Free manganese ions inhibited the enzyme activity of either ATPase. The ATPases of Hf. mediterranei and Hf. volcanii, respectively, show different sensitivities to inhibitors of ATP hydrolysis. ATP hydrolysis of isolated Hf. mediterranei ATPase was inhibited by NaN3, which was reported to be specific for F-ATPases, by nitrate and N-ethylmaleimide (NEM), which are specific inhibitors of V-ATPases. ATP hydrolysis of Haloferax mediterranei membranes was not inhibited by DCCD , but [14C]DCCD was bound to a 14 kDa peptide of the isolated, partially purified enzyme. Furthermore, the ATPase was inactivated by preincubation with 7-chloro-4-nitrobenzofurazan (NBD-Cl). The ATPase activity of Hf. volcanii membranes was inhibited by NEM but not by nitrate and NaN3. SDS gel electrophoresis of the partially purified enzyme of Haloferax mediterranei showed putative ATPase subunits of 53.5, 49, 42, 22, 21, 14, 12, and 7.5 kDa. Immunoblots showed cross reactivity between a 53 kDa peptide and anti-β (chloroplast F1), as well as between 53, 50 and 47 kDa peptides and an ATPase antibody of Methanosarcina barkeri. The results will be discussed in context with the placement of the archaebacterial ATPases (A-ATPases) between F- and V-ATPases
8
Schütze, S., i H. D. Söling. "Does a calmodulin-dependent Ca2+-regulated Mg2+-dependent ATPase contribute to hepatic microsomal calcium uptake?" Biochemical Journal 243, nr 3 (1.05.1987): 729–37. http://dx.doi.org/10.1042/bj2430729.
Pełny tekst źródłaStreszczenie:
Solubilization of microsomal proteins followed by calmodulin affinity chromatography resulted in the separation of two distinct Ca2+-Mg2+-ATPases (Ca2+-regulated Mg2+-dependent ATPases), one being insensitive to calmodulin (ATPase-1), the other being stimulated about 5-fold by calmodulin (ATPase-2). ATPase-2 accounts for only 8% of total microsomal Ca2+-Mg2+-ATPase-activity. ATPase-1 and -2 can also be distinguished by different pH optima, different sensitivity towards inhibition by vanadate and LaCl3, and different apparent Mr values of the phosphoenzyme intermediates (115,000 and 150,000 for ATPase-1 and ATPase-2 respectively). ATPase-1 from liver co-migrated with Ca2+-Mg2+-ATPase from rat skeletal-muscle sarcoplasmic reticulum, whereas ATPase-2 from liver co-migrated with calmodulin-dependent Ca2+-Mg2+-ATPase derived from rat skeletal-muscle sarcolemma. After separation of parenchymal and nonparenchymal liver cells, a calmodulin-dependent Ca2+-Mg2+-ATPase of Mr 150,000 was found only in the non-parenchymal cells. The kinetic parameters of ATPase-2 and the similarity of the apparent Mr of its phosphoenzyme intermediate to that of skeletal-muscle sarcolemma Ca2+-Mg2+-ATPase makes it likely that the calmodulin-sensitive Ca2+-Mg2+-ATPase found in rat liver microsomal fractions reflects a contamination with plasma membranes (possibly from non-parenchymal cells) rather than a true location in the endoplasmic reticulum of parenchymal liver cells.
9
Missiaen, L., F. Wuytack, H. De Smedt, M. Vrolix i R. Casteels. "AlF4- reversibly inhibits ‘P’-type cation-transport ATPases, possibly by interacting with the phosphate-binding site of the ATPase". Biochemical Journal 253, nr 3 (1.08.1988): 827–33. http://dx.doi.org/10.1042/bj2530827.
Pełny tekst źródłaStreszczenie:
The only known cellular action of AlF4- is to stimulate the G-proteins. The aim of the present work is to demonstrate that AlF4- also inhibits ‘P’-type cation-transport ATPases. NaF plus AlCl3 completely and reversibly inhibits the activity of the purified (Na+ + K+)-ATPase (Na+- and K+-activated ATPase) and of the purified plasmalemmal (Ca2+ + Mg2+)-ATPase (Ca2+-stimulated and Mg2+-dependent ATPase). It partially inhibits the activity of the sarcoplasmic-reticulum (Ca2+ + Mg2+)-ATPase, whereas it does not affect the mitochondrial H+-transporting ATPase. The inhibitory substances are neither F- nor Al3+ but rather fluoroaluminate complexes. Because AlF4- still inhibits the ATPase in the presence of guanosine 5′-[beta-thio]diphosphate, and because guanosine 5′-[beta gamma-imido]triphosphate does not inhibit the ATPase, it is unlikely that the inhibition could be due to the activation of an unknown G-protein. The time course of inhibition and the concentrations of NaF and AlCl3 required for this inhibition differ for the different ATPases. AlF4- inhibits the (Na+ + K+)-ATPase and the plasmalemmal (Ca2+ + Mg2+)-ATPase noncompetitively with respect to ATP and to their respective cationic substrates, Na+ and Ca2+. AlF4- probably binds to the phosphate-binding site of the ATPase, as the Ki for inhibition of the (Na+ + K+)-ATPase and of the plasmalemmal (Ca2+ + Mg2+)-ATPase is shifted in the presence of respectively 5 and 50 mM-Pi to higher concentrations of NaF. Moreover, AlF4- inhibits the K+-activated p-nitrophenylphosphatase of the (Na+ + K+)-ATPase competitively with respect to p-nitrophenyl phosphate. This AlF4- –induced inhibition of ‘P’-type cation-transport ATPases warns us against explaining all the effects of AlF4- on intact cells by an activation of G-proteins.
10
Imada, Katsumi, Tohru Minamino, Yumiko Uchida, Miki Kinoshita i Keiichi Namba. "Insight into the flagella type III export revealed by the complex structure of the type III ATPase and its regulator". Proceedings of the National Academy of Sciences 113, nr 13 (16.03.2016): 3633–38. http://dx.doi.org/10.1073/pnas.1524025113.
Pełny tekst źródłaStreszczenie:
FliI and FliJ form the FliI6FliJ ATPase complex of the bacterial flagellar export apparatus, a member of the type III secretion system. The FliI6FliJ complex is structurally similar to the α3β3γ complex of F1-ATPase. The FliH homodimer binds to FliI to connect the ATPase complex to the flagellar base, but the details are unknown. Here we report the structure of the homodimer of a C-terminal fragment of FliH (FliHC2) in complex with FliI. FliHC2shows an unusually asymmetric homodimeric structure that markedly resembles the peripheral stalk of the A/V-type ATPases. The FliHC2–FliI hexamer model reveals that the C-terminal domains of the FliI ATPase face the cell membrane in a way similar to the F/A/V-type ATPases. We discuss the mechanism of flagellar ATPase complex formation and a common origin shared by the type III secretion system and the F/A/V-type ATPases.
11
Gimmler, Hartmut, Lothar Schneider i Rosemarie Kaaden. "The Plasma Membrane ATPase of Dunaliella parva". Zeitschrift für Naturforschung C 44, nr 1-2 (1.02.1989): 128–38. http://dx.doi.org/10.1515/znc-1989-1-221.
Pełny tekst źródłaStreszczenie:
Abstract Plasma membrane Mg2+, Ca2+ ATPases were isolated from Dunaliella parva by differential centrifugation and subsequent sucrose gradient centrifugation and analyzed for their properties with special emphasis on ecophysiological requirements of this extremely salt-tolerant alga. Most properties (Vmax- and KM-values, substrate specificity, vanadate and DES sensitivity, resistance against ouabain) indicate that the ATPases of the plasma membrane of D. parva are basically of the same type as that found in the plasma membrane of other algae or higher plants. However, some interesting deviations from the normal characteristics of plasma membrane ATPases of plants were observed for the Dunaliella ATPases. These modifications partially may reflect adaptations of the ATPase and/or the microenvironment of the ATPase to the highly saline environment of this alga; 1) The plasma membrane ATPase of D. parva requires unusually high concentrations of divalent cations (up to 100 mM Mg2+ or Ca2+) for maximal activity. Both cations can substitute for each other. 2) The plasma membrane ATPase of D. parva is extremely resistant against salt. It was stimulated by NaCl or KC1 at concentrations up to 800 mM , whereas at higher salt concentrations the enzyme was inhibited. However, about 2.5 M NaCl was required for halfmaximal inhibition of ATPase activity. 3) The ATPase was inhibited by inhibitors of anion transport such as SITS and D ID S . which suggests direct or indirect involvement of ATPase in anion transport. The possible functions of the plasma membrane ATPases are discussed with special emphasis on problems related to the hypersaline environment of this alga.
12
Tang, Leo T. H., Meera Trivedi, Jenna Freund, Christopher J. Salazar, Maisha Rahman, Nelson J. Ramirez-Suarez, Garrett Lee, Yu Wang, Barth D. Grant i Hannes E. Bülow. "The CATP-8/P5A-type ATPase functions in multiple pathways during neuronal patterning". PLOS Genetics 17, nr 7 (1.07.2021): e1009475. http://dx.doi.org/10.1371/journal.pgen.1009475.
Pełny tekst źródłaStreszczenie:
The assembly of neuronal circuits involves the migrations of neurons from their place of birth to their final location in the nervous system, as well as the coordinated growth and patterning of axons and dendrites. In screens for genes required for patterning of the nervous system, we identified the catp-8/P5A-ATPase as an important regulator of neural patterning. P5A-ATPases are part of the P-type ATPases, a family of proteins known to serve a conserved function as transporters of ions, lipids and polyamines in unicellular eukaryotes, plants, and humans. While the function of many P-type ATPases is relatively well understood, the function of P5A-ATPases in metazoans remained elusive. We show here, that the Caenorhabditis elegans ortholog catp-8/P5A-ATPase is required for defined aspects of nervous system development. Specifically, the catp-8/P5A-ATPase serves functions in shaping the elaborately sculpted dendritic trees of somatosensory PVD neurons. Moreover, catp-8/P5A-ATPase is required for axonal guidance and repulsion at the midline, as well as embryonic and postembryonic neuronal migrations. Interestingly, not all axons at the midline require catp-8/P5A-ATPase, although the axons run in the same fascicles and navigate the same space. Similarly, not all neuronal migrations require catp-8/P5A-ATPase. A CATP-8/P5A-ATPase reporter is localized to the ER in most, if not all, tissues and catp-8/P5A-ATPase can function both cell-autonomously and non-autonomously to regulate neuronal development. Genetic analyses establish that catp-8/P5A-ATPase can function in multiple pathways, including the Menorin pathway, previously shown to control dendritic patterning in PVD, and Wnt signaling, which functions to control neuronal migrations. Lastly, we show that catp-8/P5A-ATPase is required for localizing select transmembrane proteins necessary for dendrite morphogenesis. Collectively, our studies suggest that catp-8/P5A-ATPase serves diverse, yet specific, roles in different genetic pathways and may be involved in the regulation or localization of transmembrane and secreted proteins to specific subcellular compartments.
13
Manolson, Morris F., Judith M. Percy, David K. Apps, Xiao-Song Xie, Dennis K. Stone, Michael Harrison, David J. Clarke i Ronald J. Poole. "Evolution of vacuolar H+-ATPases: immunological relationships of the nucleotide-binding subunits". Biochemistry and Cell Biology 67, nr 6 (1.06.1989): 306–10. http://dx.doi.org/10.1139/o89-047.
Pełny tekst źródłaStreszczenie:
The evolution of the endomembrane systems of eukaryotic cells can be examined by exploring the evolutionary origins of the endomembrane H+-ATPases. Recent studies suggest that certain polypeptides are common to all H+ pumps of this type. Tonoplast H+ -ATPase from Beta vulgaris L. was purified and antibodies raised to two of its subunits. Each of these antisera reacted with a polypeptide of the corresponding size in bovine chromaffin granules, bovine clathrincoated vesicles, and yeast vacuolar membranes, suggesting common structural features and a common ancestor for endomembrane H+-ATPases of different organelles and different kingdoms. The antiserum raised against the 57-kDa polypeptide of plant tonoplast H+ -ATPase also reacted with subunit "a" of the H+-ATPase from the obligately anaerobic bacterium Clostridium pasteurianum and to the α subunit of the H+ -ATPase from Escherichia coli. There was no reactivity with chloroplast or mitochondrial ATPases. These results are discussed in relation to recent sequence data which suggest that endomembrane H+-ATPases may be evolutionarily related to the F0F1 ATPases.Key words: H+ -ATPase, evolution, immunology, vacuole, endomembrane.
14
Sane, Aniruddha P., i Vidhu A. Sane. "Isolation and Kinetic Analyses of the Soluble F1 ATPases from Mitochondria of Wheat and Pearlmillet". Zeitschrift für Naturforschung C 53, nr 5-6 (1.06.1998): 341–46. http://dx.doi.org/10.1515/znc-1998-5-607.
Pełny tekst źródłaStreszczenie:
Abstract The mitochondrial F1 ATPases from two cereal crops, wheat and pearlmillet, were purified and studied. The wheat F1 ATPase could be purified to homogeneity and is apparently composed of six subunits with apparent molecular weights of 55 kDa (α and β), 35 kDa (γ), 26 kDa (δ’) and 22 kDa (δ). The e subunit was barely detectable. Both enzymes reveal typical non-linear kinetics but show variability in their response to bicarbonate and chloride. While the wheat F1 ATPase is stimulated by bicarbonate and chloride, the pearlmillet F1 ATPase is inhibited by both anions. The two enzymes are Mg2+ dependent ATPases and are competitively inhibited by Ca2+, unlike maize, pea and turnip ATPases. Both the enzymes also possess a GTPase activity which is two fold higher than the ATPase, unlike rice, sorghum and oat root F1 ATPases.
15
Burnay, Muriel, Gilles Crambert, Solange Kharoubi-Hess, Käthi Geering i Jean-Daniel Horisberger. "Bufo marinus bladder H-K-ATPase carries out electroneutral ion transport". American Journal of Physiology-Renal Physiology 281, nr 5 (1.11.2001): F869—F874. http://dx.doi.org/10.1152/ajprenal.2001.281.5.f869.
Pełny tekst źródłaStreszczenie:
Bufo marinus bladder H-K-ATPase belongs to the Na-K-ATPase and H-K-ATPase subfamily of oligomeric P-type ATPases and is closely related to rat and human nongastric H-K-ATPases. It has been demonstrated that this ATPase transports K+ into the cell in exchange for protons and sodium ions, but the stoichiometry of this cation exchange is not yet known. We studied the electrogenic properties of B. marinus bladder H-K-ATPase expressed in Xenopus laevis oocytes. In a HEPES-buffered solution, K+ activation of the H-K-ATPase induced a slow-onset inward current that reached an amplitude of ∼20 nA after 1–2 min. When measurements were performed in a solution containing 25 mM HCO[Formula: see text] at a Pco 2 of 40 Torr, the negative current activated by K+ was reduced. In noninjected oocytes, intracellular alkalization activated an inward current similar to that due to B. marinus H-K-ATPase. We conclude that the transport activity of the nongastric B. marinus H-K-ATPase is not intrinsically electrogenic but that the inward current observed in oocytes expressing this ion pump is secondary to intracellular alkalization induced by proton transport.
16
Nelson, Nathan, i William R. Harvey. "Vacuolar and Plasma Membrane Proton-Adenosinetriphosphatases". Physiological Reviews 79, nr 2 (1.04.1999): 361–85. http://dx.doi.org/10.1152/physrev.1999.79.2.361.
Pełny tekst źródłaStreszczenie:
The vacuolar H+-ATPase (V-ATPase) is one of the most fundamental enzymes in nature. It functions in almost every eukaryotic cell and energizes a wide variety of organelles and membranes. V-ATPases have similar structure and mechanism of action with F-ATPase and several of their subunits evolved from common ancestors. In eukaryotic cells, F-ATPases are confined to the semi-autonomous organelles, chloroplasts, and mitochondria, which contain their own genes that encode some of the F-ATPase subunits. In contrast to F-ATPases, whose primary function in eukaryotic cells is to form ATP at the expense of the proton-motive force (pmf), V-ATPases function exclusively as ATP-dependent proton pumps. The pmf generated by V-ATPases in organelles and membranes of eukaryotic cells is utilized as a driving force for numerous secondary transport processes. The mechanistic and structural relations between the two enzymes prompted us to suggest similar functional units in V-ATPase as was proposed to F-ATPase and to assign some of the V-ATPase subunit to one of four parts of a mechanochemical machine: a catalytic unit, a shaft, a hook, and a proton turbine. It was the yeast genetics that allowed the identification of special properties of individual subunits and the discovery of factors that are involved in the enzyme biogenesis and assembly. The V-ATPases play a major role as energizers of animal plasma membranes, especially apical plasma membranes of epithelial cells. This role was first recognized in plasma membranes of lepidopteran midgut and vertebrate kidney. The list of animals with plasma membranes that are energized by V-ATPases now includes members of most, if not all, animal phyla. This includes the classical Na+absorption by frog skin, male fertility through acidification of the sperm acrosome and the male reproductive tract, bone resorption by mammalian osteoclasts, and regulation of eye pressure. V-ATPase may function in Na+uptake by trout gills and energizes water secretion by contractile vacuoles in Dictyostelium. V-ATPase was first detected in organelles connected with the vacuolar system. It is the main if not the only primary energy source for numerous transport systems in these organelles. The driving force for the accumulation of neurotransmitters into synaptic vesicles is pmf generated by V-ATPase. The acidification of lysosomes, which are required for the proper function of most of their enzymes, is provided by V-ATPase. The enzyme is also vital for the proper function of endosomes and the Golgi apparatus. In contrast to yeast vacuoles that maintain an internal pH of ∼5.5, it is believed that the vacuoles of lemon fruit may have a pH as low as 2. Similarly, some brown and red alga maintain internal pH as low as 0.1 in their vacuoles. One of the outstanding questions in the field is how such a conserved enzyme as the V-ATPase can fulfill such diverse functions.
17
Enouf, J., R. Bredoux, N. Bourdeau, B. Sarkadi i S. Levy-Toledano. "Further characterization of the plasma membrane- and intracellular membrane-associated platelet Ca2+ transport systems". Biochemical Journal 263, nr 2 (15.10.1989): 547–52. http://dx.doi.org/10.1042/bj2630547.
Pełny tekst źródłaStreszczenie:
Biochemical characterization of the Ca2+-ATPases isolated from human platelet intracellular and plasma membranes is reported. A comparative study of the previously partly described plasma membrane Ca2+-ATPase [Enouf, Bredoux, Bourdeau & Levy-Toledano (1987) J. Biol. Chem. 261, 9293-9297] and the intracellular membrane Ca2+-ATPase obtained simultaneously shows differences in the following parameters: (1) different kinetics of the two enzymes; (2) similar apparent affinity towards Ca2+ (10(-7) M), though the intracellular membrane enzyme was inhibited at Ca2+ concentrations above 10(-6) M; (3) different pH dependence with an activity maximum at pH 7 for the intracellular membrane Ca2+-ATPase and no detectable pH maximum for the plasma membrane Ca2+-ATPase; (4) a 10-fold difference in the ATP requirement of the two Ca2+-ATPases; (5) different patterns of inhibition by vanadate. Finally, the possible regulation of the Ca2+-ATPases was examined by studying the effect of chlorpromazine on the two Ca2+-ATPase activities, with only the plasma membrane enzyme being inhibited. It is concluded that the two platelet Ca2+ transport systems show biochemical differences in spite of the previously shown similarity in the molecular masses of their Ca2+-ATPases, thus conferring a definite specificity to the platelet system.
18
Collaco, Anne M., Peter Geibel, Beth S. Lee, John P. Geibel i Nadia A. Ameen. "Functional vacuolar ATPase (V-ATPase) proton pumps traffic to the enterocyte brush border membrane and require CFTR". American Journal of Physiology-Cell Physiology 305, nr 9 (1.11.2013): C981—C996. http://dx.doi.org/10.1152/ajpcell.00067.2013.
Pełny tekst źródłaStreszczenie:
Vacuolar ATPases (V-ATPases) are highly conserved proton pumps that regulate organelle pH. Epithelial luminal pH is also regulated by cAMP-dependent traffic of specific subunits of the V-ATPase complex from endosomes into the apical membrane. In the intestine, cAMP-dependent traffic of cystic fibrosis transmembrane conductance regulator (CFTR) channels and the sodium hydrogen exchanger (NHE3) in the brush border regulate luminal pH. V-ATPase was found to colocalize with CFTR in intestinal CFTR high expresser (CHE) cells recently. Moreover, apical traffic of V-ATPase and CFTR in rat Brunner's glands was shown to be dependent on cAMP/PKA. These observations support a functional relationship between V-ATPase and CFTR in the intestine. The current study examined V-ATPase and CFTR distribution in intestines from wild-type, CFTR−/−mice and polarized intestinal CaCo-2BBe cells following cAMP stimulation and inhibition of CFTR/V-ATPase function. Coimmunoprecipitation studies examined V-ATPase interaction with CFTR. The pH-sensitive dye BCECF determined proton efflux and its dependence on V-ATPase/CFTR in intestinal cells. cAMP increased V-ATPase/CFTR colocalization in the apical domain of intestinal cells and redistributed the V-ATPase Voa1 and Voa2 trafficking subunits from the basolateral membrane to the brush border membrane. Voa1 and Voa2 subunits were localized to endosomes beneath the terminal web in untreated CFTR−/−intestine but redistributed to the subapical cytoplasm following cAMP treatment. Inhibition of CFTR or V-ATPase significantly decreased pHiin cells, confirming their functional interdependence. These data establish that V-ATPase traffics into the brush border membrane to regulate proton efflux and this activity is dependent on CFTR in the intestine.
19
Sautin, Yuri Y., Ming Lu, Andrew Gaugler, Li Zhang i Stephen L. Gluck. "Phosphatidylinositol 3-Kinase-Mediated Effects of Glucose on Vacuolar H+-ATPase Assembly, Translocation, and Acidification of Intracellular Compartments in Renal Epithelial Cells". Molecular and Cellular Biology 25, nr 2 (15.01.2005): 575–89. http://dx.doi.org/10.1128/mcb.25.2.575-589.2005.
Pełny tekst źródłaStreszczenie:
ABSTRACT Vacuolar H+-ATPases (V-ATPases) are a family of ATP-driven proton pumps. They maintain pH gradients between intracellular compartments and are required for proton secretion out of the cytoplasm. Mechanisms of extrinsic control of V-ATPase are poorly understood. Previous studies showed that glucose is an important regulator of V-ATPase assembly in Saccharomyces cerevisiae. Human V-ATPase directly interacts with aldolase, providing a coupling mechanism for glucose metabolism and V-ATPase function. Here we show that glucose is a crucial regulator of V-ATPase in renal epithelial cells and that the effect of glucose is mediated by phosphatidylinositol 3-kinase (PI3K). Glucose stimulates V-ATPase-dependent acidification of the intracellular compartments in human proximal tubular cells HK-2 and porcine renal epithelial cells LLC-PK1. Glucose induces rapid ATP-independent assembly of the V1 and Vo domains of V-ATPase and extensive translocation of the V-ATPase V1 and Vo domains between different membrane pools and between membranes and the cytoplasm. In HK-2 cells, glucose stimulates polarized translocation of V-ATPase to the apical plasma membrane. The effects of glucose on V-ATPase trafficking and assembly can be abolished by pretreatment with the PI3K inhibitor LY294002 and can be reproduced in glucose-deprived cells by adenoviral expression of the constitutively active catalytic subunit p110α of PI3K. Taken together these data provide evidence that, in renal epithelial cells, glucose plays an important role in the control of V-ATPase-dependent acidification of intracellular compartments and V-ATPase assembly and trafficking and that the effects of glucose are mediated by PI3K-dependent signaling.
20
Bychkova, Solomiia, Mykola Bychkov, Dani Dordevic, Monika Vítězová, Simon K. M. R. Rittmann i Ivan Kushkevych. "Bafilomycin A1 Molecular Effect on ATPase Activity of Subcellular Fraction of Human Colorectal Cancer and Rat Liver". International Journal of Molecular Sciences 25, nr 3 (29.01.2024): 1657. http://dx.doi.org/10.3390/ijms25031657.
Pełny tekst źródłaStreszczenie:
Bafilomycin A1 inhibits V-type H+ ATPases on the molecular level, which acidifies endo-lysosomes. The main objective of the study was to assess the effect of bafilomycin A1 on Ca2+ content, NAADP-induced Ca2+ release, and ATPase activity in rat hepatocytes and human colon cancer samples. Chlortetracycline (CTC) was used for a quantitative measure of stored calcium in permeabilized rat hepatocytes. ATPase activity was determined by orthophosphate content released after ATP hydrolysis in subcellular post-mitochondrial fraction obtained from rat liver as well as from patients’ samples of colon mucosa and colorectal cancer samples. In rat hepatocytes, bafilomycin A1 decreased stored Ca2+ and prevented the effect of NAADP on stored Ca2+. This effect was dependent on EGTA–Ca2+ buffers in the medium. Bafilomycin A1 significantly increased the activity of Ca2+ ATPases of endoplasmic reticulum (EPR), but not plasma membrane (PM) Ca2+ ATPases in rat liver. Bafilomycin A1 also prevented the effect of NAADP on these pumps. In addition, bafilomycin A1 reduced Na+/K+ ATPase activity and increased basal Mg2+ ATPase activity in the subcellular fraction of rat liver. Concomitant administration of bafilomycin A1 and NAADP enhanced these effects. Bafilomycin A1 increased the activity of the Ca2+ ATPase of EPR in the subcellular fraction of normal human colon mucosa and also in colon cancer tissue samples. In contrast, it decreased Ca2+ ATPase PM activity in samples of normal human colon mucosa and caused no changes in colon cancer. Bafilomycin A1 decreased Na+/K+ ATPase activity and increased basal Mg2+ ATPase activity in normal colon mucosa samples and in human colon cancer samples. It can be concluded that bafilomycin A1 targets NAADP-sensitive acidic Ca2+ stores, effectively modulates ATPase activity, and assumes the link between acidic stores and EPR. Bafilomycin A1 may be useful for cancer therapy.
21
Grover, A. K., C. Y. Kwan i P. J. Oakes. "Calcium pump, high-affinity Ca2+-ATPase, and other ATPases in dog antrum smooth muscle plasma membrane". American Journal of Physiology-Cell Physiology 248, nr 5 (1.05.1985): C449—C456. http://dx.doi.org/10.1152/ajpcell.1985.248.5.c449.
Pełny tekst źródłaStreszczenie:
The plasma membrane-enriched fraction from dog antrum smooth muscle is enriched in ATP-dependent azide-insensitive Ca2+ uptake (0.3-0.4 microM Ca2+ required for half-maximal activity), a high-affinity Ca2+-ATPase (Km of 0.3-0.8 microM for Ca2+), a low-affinity Ca2+-ATPase (Km for 250-400 microM for Ca2+), and a Mg2+-ATPase. Studies using membranes washed with EDTA and assay media treated with Chelex 100 showed that the high-affinity Ca2+-ATPase did not depend on contaminating Mg2+. Thus, whereas the ATP-dependent Ca2+ uptake had an absolute requirement for Mg2+, the Ca2+-ATPases did not. Studies using gamma-irradiation showed that the protein responsible for the ATP-dependent Ca2+ uptake was inactivated at significantly lower doses of radiation than the three ATPases. The Ca2+ uptake and the high-affinity Ca2+-ATPase also differed in their inhibition by calmodulin antagonists and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. Thus it is unlikely that the high-affinity Ca2+-ATPase by itself is responsible for the ATP-dependent Ca2+ uptake.
22
Kane, Patricia M. "The Where, When, and How of Organelle Acidification by the Yeast Vacuolar H+-ATPase". Microbiology and Molecular Biology Reviews 70, nr 1 (marzec 2006): 177–91. http://dx.doi.org/10.1128/mmbr.70.1.177-191.2006.
Pełny tekst źródłaStreszczenie:
SUMMARY All eukaryotic cells contain multiple acidic organelles, and V-ATPases are central players in organelle acidification. Not only is the structure of V-ATPases highly conserved among eukaryotes, but there are also many regulatory mechanisms that are similar between fungi and higher eukaryotes. These mechanisms allow cells both to regulate the pHs of different compartments and to respond to changing extracellular conditions. The Saccharomyces cerevisiae V-ATPase has emerged as an important model for V-ATPase structure and function in all eukaryotic cells. This review discusses current knowledge of the structure, function, and regulation of the V-ATPase in S. cerevisiae and also examines the relationship between biosynthesis and transport of V-ATPase and compartment-specific regulation of acidification.
23
Buffin-Meyer, B., M. Younes-Ibrahim, C. Barlet-Bas, L. Cheval, S. Marsy i A. Doucet. "K depletion modifies the properties of Sch-28080-sensitive K-ATPase in rat collecting duct". American Journal of Physiology-Renal Physiology 272, nr 1 (1.01.1997): F124—F131. http://dx.doi.org/10.1152/ajprenal.1997.272.1.f124.
Pełny tekst źródłaStreszczenie:
Two distinct Sch-28080-sensitive K-adenosine triphosphatases (K-ATPases) were previously described in the rat nephron: a ouabain-resistant K-ATPase (type I) present in collecting ducts (CD) and a ouabain-sensitive from (type II) located in proximal tubules (PT) and thick ascending limbs (TAL). In K-depleted rats, K-ATPase activity is increased in CD, whereas it is reduced in PT and TAL. Because expression of colonic H-K-ATPase is restricted to the CD of K-depleted rats, we hypothesized that K-ATPase from the CD of K-depleted rats might be different from types I and II. Indeed, type III K-ATPase displays higher sensitivities to ouabain and to Sch-28080 than type II, a lower sensitivity to Sch-28080 than type I, and, conversely to types I and II, it can be stimulated by Na+. Pharmacological differences between types II and III K-ATPases were confirmed by [3H]ouabain binding experiments. Thus the rat kidney expresses three K-ATPases that differ by their pharmacological and kinetic properties, their distribution profile along the nephron and their behavior during K depletion.
24
Gogarten, J. P., T. Starke, H. Kibak, J. Fishman i L. Taiz. "Evolution and isoforms of V-ATPase subunits." Journal of Experimental Biology 172, nr 1 (1.11.1992): 137–47. http://dx.doi.org/10.1242/jeb.172.1.137.
Pełny tekst źródłaStreszczenie:
The structure of V- and F-ATPases/ATP synthases is remarkably conserved throughout evolution. Sequence analyses show that the V- and F-ATPases evolved from the same enzyme that was already present in the last common ancestor of all known extant life forms. The catalytic and non-catalytic subunits found in the dissociable head groups of both V-ATPases and F-ATPases are paralogous subunits, i.e. these two types of subunits evolved from a common ancestral gene. The gene duplication giving rise to these two genes (i.e. those encoding the catalytic and non-catalytic subunits) pre-dates the time of the last common ancestor. Similarities between the V- and F-ATPase subunits and an ATPase-like protein that is implicated in flagellar assembly are evaluated with regard to the early evolution of ATPases. Mapping of gene duplication events that occurred in the evolution of the proteolipid, the non-catalytic and the catalytic subunits onto the tree of life leads to a prediction of the likely quaternary structure of the encoded ATPases. The phylogenetic implications of V-ATPases found in eubacteria are discussed. Different V-ATPase isoforms have been detected in some higher eukaryotes, whereas others were shown to have only a single gene encoding the catalytic V-ATPase subunit. These data are analyzed with respect to the possible function of the different isoforms (tissue-specific, organelle-specific). The point in evolution at which the different isoforms arose is mapped by phylogenetic analysis.
25
Schep, Daniel G., Jianhua Zhao i John L. Rubinstein. "Models for the a subunits of the Thermus thermophilus V/A-ATPase and Saccharomyces cerevisiae V-ATPase enzymes by cryo-EM and evolutionary covariance". Proceedings of the National Academy of Sciences 113, nr 12 (7.03.2016): 3245–50. http://dx.doi.org/10.1073/pnas.1521990113.
Pełny tekst źródłaStreszczenie:
Rotary ATPases couple ATP synthesis or hydrolysis to proton translocation across a membrane. However, understanding proton translocation has been hampered by a lack of structural information for the membrane-embedded a subunit. The V/A-ATPase from the eubacterium Thermus thermophilus is similar in structure to the eukaryotic V-ATPase but has a simpler subunit composition and functions in vivo to synthesize ATP rather than pump protons. We determined the T. thermophilus V/A-ATPase structure by cryo-EM at 6.4 Å resolution. Evolutionary covariance analysis allowed tracing of the a subunit sequence within the map, providing a complete model of the rotary ATPase. Comparing the membrane-embedded regions of the T. thermophilus V/A-ATPase and eukaryotic V-ATPase from Saccharomyces cerevisiae allowed identification of the α-helices that belong to the a subunit and revealed the existence of previously unknown subunits in the eukaryotic enzyme. Subsequent evolutionary covariance analysis enabled construction of a model of the a subunit in the S. cerevisae V-ATPase that explains numerous biochemical studies of that enzyme. Comparing the two a subunit structures determined here with a structure of the distantly related a subunit from the bovine F-type ATP synthase revealed a conserved pattern of residues, suggesting a common mechanism for proton transport in all rotary ATPases.
26
Laroche-Joubert, Nicolas, Sophie Marsy i Alain Doucet. "Cellular origin and hormonal regulation of K+-ATPase activities sensitive to Sch-28080 in rat collecting duct". American Journal of Physiology-Renal Physiology 279, nr 6 (1.12.2000): F1053—F1059. http://dx.doi.org/10.1152/ajprenal.2000.279.6.f1053.
Pełny tekst źródłaStreszczenie:
Rat collecting ducts exhibit type I or type III K+-ATPase activities when animals are fed a normal (NK) or a K+-depleted diet (LK). This study aimed at determining functionally the cell origin of these two K+-ATPases. For this purpose, we searched for an effect on K+-ATPases of hormones that trigger cAMP production in a cell-specific fashion. The effects of 1-deamino-8-d-arginine vasopressin (dD-AVP), calcitonin, and isoproterenol in principal cells, α-intercalated cells, and β-intercalated cells of cortical collecting duct (CCD), respectively, and of dD-AVP and glucagon in principal and α-intercalated cells of outer medullary collecting duct (OMCD), respectively, were examined. In CCDs, K+-ATPase was stimulated by calcitonin and isoproterenol in NK rats (type I K+-ATPase) and by dD-AVP in LK rats (type III K+-ATPase). In OMCDs, dD-AVP and glucagon stimulated type III but not type I K+-ATPase. These hormone effects were mimicked by the cAMP-permeant analog dibutyryl-cAMP. In conclusion, in NK rats, cAMP stimulates type I K+-ATPase activity in α- and β-intercalated CCD cells, whereas in LK rats it stimulates type III K+-ATPase in principal cells of both CCD and OMCD and in OMCD intercalated cells.
27
Bowman, B. J., W. J. Dschida i E. J. Bowman. "Vacuolar ATPase of Neurospora crassa: electron microscopy, gene characterization and gene inactivation/mutation." Journal of Experimental Biology 172, nr 1 (1.11.1992): 57–66. http://dx.doi.org/10.1242/jeb.172.1.57.
Pełny tekst źródłaStreszczenie:
We are using three approaches to investigate the vacuolar ATPase, V-ATPase, from Neurospora crassa. (1) Examination in the electron microscope shows the enzyme has a 'ball and stalk' structure like the F-type ATPases. However, the vacuolar ATPase is significantly larger, has a prominent cleft in the head sector, and has extra components associated with the stalk and membrane sectors. (2) Genes encoding three of the major subunits of the vacuolar ATPase and the homologous subunits of the mitochondrial F-ATPase have been isolated. The exon/intron structures of the genes have been analyzed and the chromosomal locations have been determined. Two of the vacuolar ATPase genes map very close to each other, suggesting the possibility of a cluster of ATPase genes. (3) The function of the ATPase is being investigated by isolating strains with altered or inactivated ATPase. We are characterizing strains that are resistant to bafilomycin A1, a potent and specific inhibitor of the vacuolar ATPase. Initial attempts to inactivate a vacuolar ATPase gene indicate that the enzyme may be essential for growth.
28
Forgac, M. "Structure, mechanism and regulation of the clathrin-coated vesicle and yeast vacuolar H(+)-ATPases". Journal of Experimental Biology 203, nr 1 (1.01.2000): 71–80. http://dx.doi.org/10.1242/jeb.203.1.71.
Pełny tekst źródłaStreszczenie:
The vacuolar H(+)-ATPases (or V-ATPases) are a family of ATP-dependent proton pumps that carry out acidification of intracellular compartments in eukaryotic cells. This review is focused on our work on the V-ATPases of clathrin-coated vesicles and yeast vacuoles. The coated-vesicle V-ATPase undergoes trafficking to endosomes and synaptic vesicles, where it functions in receptor recycling and neurotransmitter uptake, respectively. The yeast V-ATPase functions to acidify the central vacuole and is necessary both for protein degradation and for coupled transport processes across the vacuolar membrane. The V-ATPases are multisubunit complexes composed of two functional domains. The V(1) domain is a 570 kDa peripheral complex composed of eight subunits of molecular mass 73–14 kDa (subunits A-H) that is responsible for ATP hydrolysis. The V(o) domain is a 260 kDa integral complex composed of five subunits of molecular mass 100-17 kDa (subunits a, d, c, c' and c”) that is responsible for proton translocation. To explore the function of individual subunits in the V-ATPase complex as well as to identify residues important in proton transport and ATP hydrolysis, we have employed a combination of chemical modification, site-directed mutagenesis and in vitro reassembly. A central question concerns the mechanism by which vacuolar acidification is controlled in eukaryotic cells. We have proposed that disulfide bond formation between conserved cysteine residues at the catalytic site of the V-ATPase plays an important role in regulating V-ATPase activity in vivo. Other regulatory mechanisms that are discussed include reversible dissociation and reassembly of the V-ATPase complex, changes in the tightness of coupling between proton transport and ATP hydrolysis, differential targeting of V-ATPases within the cell and control of the Cl(−) conductance that is necessary for vacuolar acidification.
29
Abe, Michiko, Mayu Saito, Ayana Tsukahara, Shuka Shiokawa, Kazuma Ueno, Hiroki Shimamura, Makoto Nagano, Junko Y. Toshima i Jiro Toshima. "Functional complementation reveals that 9 of the 13 human V-ATPase subunits can functionally substitute for their yeast orthologs". Journal of Biological Chemistry 294, nr 20 (5.04.2019): 8273–85. http://dx.doi.org/10.1074/jbc.ra118.006192.
Pełny tekst źródłaStreszczenie:
Vacuolar-type H+-ATPase (V-ATPase) is a highly conserved proton pump responsible for acidification of intracellular organelles and potential drug target. It is a multisubunit complex comprising a cytoplasmic V1 domain responsible for ATP hydrolysis and a membrane-embedded Vo domain that contributes to proton translocation across the membrane. Saccharomyces cerevisiae V-ATPase is composed of 14 subunits, deletion of any one of which results in well-defined growth defects. As the structure of V-ATPase and the function of each subunit have been well-characterized in yeast, this organism has been recognized as a preferred model for studies of V-ATPases. In this study, to assess the functional relatedness of the yeast and human V-ATPase subunits, we investigated whether human V-ATPase subunits can complement calcium- or pH-sensitive growth, acidification of the vacuolar lumen, assembly of the V-ATPase complex, and protein sorting in yeast mutants lacking the equivalent yeast genes. These assessments revealed that 9 of the 13 human V-ATPase subunits can partially or fully complement the function of the corresponding yeast subunits. Importantly, sequence similarity was not necessarily correlated with functional complementation. We also found that besides all Vo domain subunits, the V1 F subunit is required for proper assembly of the Vo domain at the endoplasmic reticulum. Furthermore, the human H subunit fully restored the level of vacuolar acidification, but only partially rescued calcium-sensitive growth, suggesting a specific role of the H subunit in V-ATPase activity. These findings provide important insights into functional homologies between yeast and human V-ATPases.
30
Garg, L. C. "Respective roles of H-ATPase and H-K-ATPase in ion transport in the kidney." Journal of the American Society of Nephrology 2, nr 5 (listopad 1991): 949–60. http://dx.doi.org/10.1681/asn.v25949.
Pełny tekst źródłaStreszczenie:
Two types of proton-translocating ATPases, H-ATPase and H-K-ATPase, are found in the renal tubular cells. H-ATPase is present in both endocytic vesicles and apical membranes in almost all nephron segments. On the other hand, H-K-ATPase is present only in the connecting tubule and collecting duct. There is evidence to suggest that H-ATPase may be involved in H secretion in almost all nephron segments. H-K-ATPase is involved not only in H secretion but also in K absorption in the collecting duct segments. Aldosterone administration and metabolic acidosis stimulate the activity of H-ATPase in all collecting duct segments, whereas hypokalemia has only a limited effect on H-ATPase activity. On the other hand, hypokalemia, as well as metabolic acidosis, stimulates H-K-ATPase activity in the collecting duct segments, whereas aldosterone administration alone plays a minor role in the regulation of this enzyme. The physiological role and regulation of H-ATPase in the proximal tubule has not been established.
31
Purohit, Rahul, Matthew O. Ross, Sharon Batelu, April Kusowski, Timothy L. Stemmler, Brian M. Hoffman i Amy C. Rosenzweig. "Cu+-specific CopB transporter: Revising P1B-type ATPase classification". Proceedings of the National Academy of Sciences 115, nr 9 (12.02.2018): 2108–13. http://dx.doi.org/10.1073/pnas.1721783115.
Pełny tekst źródłaStreszczenie:
The copper-transporting P1B-ATPases, which play a key role in cellular copper homeostasis, have been divided traditionally into two subfamilies, the P1B-1-ATPases or CopAs and the P1B-3-ATPases or CopBs. CopAs selectively export Cu+ whereas previous studies and bioinformatic analyses have suggested that CopBs are specific for Cu2+ export. Biochemical and spectroscopic characterization of Sphaerobacter thermophilus CopB (StCopB) show that, while it does bind Cu2+, the binding site is not the prototypical P1B-ATPase transmembrane site and does not involve sulfur coordination as proposed previously. Most important, StCopB exhibits metal-stimulated ATPase activity in response to Cu+, but not Cu2+, indicating that it is actually a Cu+ transporter. X-ray absorption spectroscopic studies indicate that Cu+ is coordinated by four sulfur ligands, likely derived from conserved cysteine and methionine residues. The histidine-rich N-terminal region of StCopB is required for maximal activity, but is inhibitory in the presence of divalent metal ions. Finally, reconsideration of the P1B-ATPase classification scheme suggests that the P1B-1- and P1B-3-ATPase subfamilies both comprise Cu+ transporters. These results are completely consistent with the known presence of only Cu+ within the reducing environment of the cytoplasm, which should eliminate the need for a Cu2+ P1B-ATPase.
32
Monk, B. C., A. B. Mason, T. B. Kardos i D. S. Perlin. "Targeting the fungal plasma membrane proton pump." Acta Biochimica Polonica 42, nr 4 (31.12.1995): 481–96. http://dx.doi.org/10.18388/abp.1995_4901.
Pełny tekst źródłaStreszczenie:
The need for new mechanistic classes of broad spectrum antifungal agents has prompted development of the membrane sector and ectodomain of the plasma membrane proton pumping ATPase as an antifungal target. The fungal proton pump is a highly abundant, essential enzyme in Saccharomyces cerevisiae. It belongs to the family of P-type ATPases, a class of enzymes that includes the Na+,K(+)-ATPase and the gastric H+,K(+)-ATPase. These enzymes are cell surface therapeutic targets for the cardiac glycosides and several anti-ulcer drugs, respectively. The effects of acid-activated omeprazole show that extensive inhibition of the S. cerevisiae ATPase is fungicidal. Fungal proton pumps possess elements within their transmembrane loops that distinguish them from other P-type ATPases. These loops, such as the conformationally sensitive transmembrane loop 1+2, can attenuate the activity of the enzyme. Expression in S. cerevisiae of fully functional chimeric ATPases that contain a foreign target comprising transmembrane loops 1+2 and/or 3+4 from the fungal pathogen Candida albicans suggests that these loops operate as a domain. The chimera containing C. albicans transmembrane loops 1+2 and 3+4 provides a prototype for mutational analysis of the target region and the screening of inhibitors directed against opportunistic fungal pathogens. Panels of mutants with modified ATPase regulation or with altered cell surface cysteine residues are also described. Information about the ATPase membrane sector and ectodomain has been integrated into a model of this region.
33
Murakami, K., K. Tanabe i S. Takada. "Structure of a Plasmodium yoelii gene-encoded protein homologous to the Ca(2+)-ATPase of rabbit skeletal muscle sarcoplasmic reticulum". Journal of Cell Science 97, nr 3 (1.11.1990): 487–95. http://dx.doi.org/10.1242/jcs.97.3.487.
Pełny tekst źródłaStreszczenie:
A cation-transporting ATPase gene of Plasmodium yoelii was cloned from the parasite genomic library using an oligonucleotide probe derived from a conserved amino acid sequence of the phosphorylation domain of the aspartyl phosphate family of ATPases. The complete nucleotide sequence was determined and it predicts a 126,717 Mr encoded protein composed of 1115 amino acids. Northern blot analysis revealed that the gene is transcribed during the asexual stages of parasite development. The P. yoelii protein contains functional and structural features common to the family of aspartyl phosphate cation-transporting ATPases. The parasite protein shows the highest overall homology in amino acid sequence (42%) to the Ca2(+)-ATPase of rabbit skeletal muscle sarcoplasmic reticulum. Homologies to other aspartyl phosphate cation-transporting ATPases including a plasma membrane Ca2(+)-ATPase were between 13 and 24%. The structure predicted from a hydropathy plot also shows 10 transmembrane domains, the number and location of which correlated well with the sarcoplasmic reticulum Ca2(+)-ATPase. On the basis of these results, we conclude that the parasite gene encodes an organellar, but not plasma membrane, Ca2(+)-ATPase. The P. yoelii protein, furthermore, contains all six amino acid residues in the transmembrane domains that were recently identified as comprising a high-affinity Ca2(+)-binding site. It follows that organellar Ca2(+)-ATPases of rabbit and Plasmodium conserve functionally important amino acid residues, even though they are remote from each other phylogenetically.
34
Eiam-ong, S., M. E. Laski, N. A. Kurtzman i S. Sabatini. "Effect of respiratory acidosis and respiratory alkalosis on renal transport enzymes". American Journal of Physiology-Renal Physiology 267, nr 3 (1.09.1994): F390—F399. http://dx.doi.org/10.1152/ajprenal.1994.267.3.f390.
Pełny tekst źródłaStreszczenie:
We studied the effect of respiratory acidosis and respiratory alkalosis on acid-base composition and on microdissected renal adenosinetriphosphatase (ATPase) enzymes. Rats were subjected to hypercapnia or hypocapnia of 6, 24, and 72 h duration. After 6 h of hypercapnia, collecting tubule (CT) ATPases were not changed. At 24 h, plasma bicarbonate was 35 +/- 1 meq/l (P < 0.01) and CT H-ATPase and H-K-ATPase activities were 90% greater than controls (P < 0.01). By 72 h, plasma bicarbonate was 37 +/- 1 meq/l (P < 0.005 vs. control) and CT enzyme activity had increased even more, averaging approximately 130% of control (P < 0.05). Significant increases in enzyme activities were also observed in the proximal convoluted tubule and medullary thick ascending limb. Plasma aldosterone was three to four times that of control at all three time periods. In hormone-replete adrenalectomized rats, acid-base parameters and ATPase activities were the same as those seen in adrenal intact animals. After 6 h of hypocapnia, plasma bicarbonate was not significantly changed, but H-ATPase and Na-K-ATPase activities were decreased by 35% along the entire nephron (P < 0.05). H-K-ATPase activity in CT also decreased by 35%. At 24 h, plasma bicarbonate was 20.5 +/- 0.5 meq/l (P < 0.05 vs. control) and CT H-ATPase and H-K-ATPase activities were 60% less than control (P < 0.01). By 72 h, plasma bicarbonate was 18.5 +/- 0.5 meq/l (P < 0.05); however, only CT H-ATPase activity continued to fall, averaging 75% less than control (P < 0.005). Hypocapnia had no effect on plasma aldosterone or potassium. These results demonstrate that chronic, but not acute, respiratory acidosis stimulates activity of both renal proton ATPases. By contrast, both acute and chronic respiratory alkalosis decrease the two renal proton pumps. The stimulatory effect of hypercapnia and the inhibitory effect of hypocapnia on the renal ATPases appear to be potassium and aldosterone independent. Although the precise mechanisms for these results are not known, a direct effect of PCO2, pH, or changes in bicarbonate delivery may be involved.
35
Smardon, Anne M., Heba I. Diab, Maureen Tarsio, Theodore T. Diakov, Negin Dehdar Nasab, Robert W. West i Patricia M. Kane. "The RAVE complex is an isoform-specific V-ATPase assembly factor in yeast". Molecular Biology of the Cell 25, nr 3 (luty 2014): 356–67. http://dx.doi.org/10.1091/mbc.e13-05-0231.
Pełny tekst źródłaStreszczenie:
The regulator of ATPase of vacuoles and endosomes (RAVE) complex is implicated in vacuolar H+-translocating ATPase (V-ATPase) assembly and activity. In yeast, rav1∆ mutants exhibit a Vma− growth phenotype characteristic of loss of V-ATPase activity only at high temperature. Synthetic genetic analysis identified mutations that exhibit a full, temperature-independent Vma− growth defect when combined with the rav1∆ mutation. These include class E vps mutations, which compromise endosomal sorting. The synthetic Vma− growth defect could not be attributed to loss of vacuolar acidification in the double mutants, as there was no vacuolar acidification in the rav1∆ mutant. The yeast V-ATPase a subunit is present as two isoforms, Stv1p in Golgi and endosomes and Vph1p in vacuoles. Rav1p interacts directly with the N-terminal domain of Vph1p. STV1 overexpression suppressed the growth defects of both rav1∆ and rav1∆vph1∆, and allowed RAVE-independent assembly of active Stv1p-containing V-ATPases in vacuoles. Mutations causing synthetic genetic defects in combination with rav1∆ perturbed the normal localization of Stv1–green fluorescent protein. We propose that RAVE is necessary for assembly of Vph1-containing V-ATPase complexes but not Stv1-containing complexes. Synthetic Vma− phenotypes arise from defects in Vph1p-containing complexes caused by rav1∆, combined with defects in Stv1p-containing V-ATPases caused by the second mutation. Thus RAVE is the first isoform-specific V-ATPase assembly factor.
36
Caplan, M. J. "Ion pumps in epithelial cells: sorting, stabilization, and polarity". American Journal of Physiology-Gastrointestinal and Liver Physiology 272, nr 6 (1.06.1997): G1304—G1313. http://dx.doi.org/10.1152/ajpgi.1997.272.6.g1304.
Pełny tekst źródłaStreszczenie:
The P-type family of ion-transporting ATPases includes all of the isoforms of Na(+)-K(+)-adenosinetriphosphatase (ATPase), the plasma membrane and organellar Ca(2+)-ATPases, gastric H(+)-K(+)-ATPase, and the recently characterized nongastric H(+)-K(+)-ATPases, among others. In epithelial cells, members of this pump family generate the cation gradients responsible for vectorial fluid and solute transport. To carry out this function, each P-type ATPase must be restricted to a specific membrane domain. Newly synthesized ion pumps must be sorted to their appropriate destinations and retained there after their delivery. Recently, progress has been made toward understanding the signals and targeting pathways that epithelial cells employ to generate anisotropic pump distributions. The mechanisms involved in generating these pump distributions may serve as well to regulate pump function.
37
Harada, Akiko, Yoshiji Okazaki, Toshinori Kinoshita, Reiko Nagai i Shingo Takagi. "Role of Proton Motive Force in Photoinduction of Cytoplasmic Streaming in Vallisneria Mesophyll Cells". Plants 9, nr 3 (18.03.2020): 376. http://dx.doi.org/10.3390/plants9030376.
Pełny tekst źródłaStreszczenie:
In mesophyll cells of the aquatic monocot Vallisneria, red light induces rotational cytoplasmic streaming, which is regulated by the cytoplasmic concentration of Ca2+. Our previous investigations revealed that red light induces Ca2+ efflux across the plasma membrane (PM), and that both the red light-induced cytoplasmic streaming and the Ca2+ efflux are sensitive to vanadate, an inhibitor of P-type ATPases. In this study, pharmacological experiments suggested the involvement of PM H+-ATPase, one of the P-type ATPases, in the photoinduction of cytoplasmic streaming. We hypothesized that red light would activate PM H+-ATPase to generate a large H+ motive force (PMF) in a photosynthesis-dependent manner. We demonstrated that indeed, photosynthesis increased the PMF and induced phosphorylation of the penultimate residue, threonine, of PM H+-ATPase, which is a major activation mechanism of H+-ATPase. The results suggested that a large PMF generated by PM H+-ATPase energizes the Ca2+ efflux across the PM. As expected, we detected a putative Ca2+/H+ exchange activity in PM vesicles isolated from Vallisneria leaves.
38
Zhao, Bingqian, Haicheng Wu, Wenjing Xu, Wei Zhang, Xi Chen, Yiyong Zhu, Huatao Chen i Houqing Zeng. "Genome-Wide Identification, Characterization, and Expression Analyses of P-Type ATPase Superfamily Genes in Soybean". Agronomy 11, nr 1 (31.12.2020): 71. http://dx.doi.org/10.3390/agronomy11010071.
Pełny tekst źródłaStreszczenie:
P-type ATPases are transmembrane pumps of cations and phospholipids. They are energized by hydrolysis of ATP and play important roles in a wide range of fundamental cellular and physiological processes during plant growth and development. However, the P-type ATPase superfamily genes have not been characterized in soybean. Here, we performed genome-wide bioinformatic and expression analyses of the P-type ATPase superfamily genes in order to explore the potential functions of P-type ATPases in soybean. A total of 105 putative P-type ATPase genes were identified in the soybean genome. Phylogenetic relationship analysis of the P-type ATPase genes indicated that they can be divided into five subfamilies including P1B, P2A/B, P3A, P4 and P5. Proteins belonging to the same subfamily shared conserved domains. Forty-seven gene pairs were related to segmental duplication, which contributed to the expansion of the P-type ATPase genes during the evolution of soybean. Most of the P-type ATPase genes contained hormonal- and/or stress-related cis-elements in their promoter regions. Expression analysis by retrieving RNA-sequencing datasets suggested that almost all of the P-type ATPase genes could be detected in soybean tissues, and some genes showed tissue-specific expression patterns. Nearly half of the P-type ATPase genes were found to be significantly induced or repressed under stresses like salt, drought, cold, flooding, and/or phosphate starvation. Four genes were significantly affected by rhizobia inoculation in root hairs. The induction of two P2B-ATPase genes, GmACA1 and GmACA2, by phosphate starvation was confirmed by quantitative RT-PCR. This study provides information for understanding the evolution and biological functions of the P-type ATPase superfamily genes in soybean.
39
Aizman, R. I., G. Celsi, L. Grahnquist, Z. M. Wang, Y. Finkel i A. Aperia. "Ontogeny of K+ transport in rat distal colon". American Journal of Physiology-Gastrointestinal and Liver Physiology 271, nr 2 (1.08.1996): G268—G274. http://dx.doi.org/10.1152/ajpgi.1996.271.2.g268.
Pełny tekst źródłaStreszczenie:
Infants need to retain more K+ than adults to avoid growth retardation. Since the K+ requirements are different in infants (I) and in adults (A), the mechanisms regulating K+ homeostasis should also be different. The colon plays an important role for the regulation of K+ homeostasis. Colonic K+ transport is bidirectional. In this study we have examined the development of colonic K+ transport with special reference to the contribution of different K(+)-transporting pathways. The net colonic K+ uptake, as determined by in vivo perfusion studies and by 86Rb uptake, was significantly higher in I than in A rats. In both I and A colon, approximately 80% of total 86Rb uptake was dependent on vanadate-sensitive P-type adenosinetriphosphatases (ATPases), but the contribution of these different ATPases changes during development. The activity of colonic Na(+)-K(+)-ATPase, measured as ouabain-sensitive Na(+)-dependent ATP hydrolysis and as 86Rb uptake, was lower in I than in A rats. In contrast, the activity of K(+)-ATPases located in apical membrane and measured as ouabain insensitive and SCH-28080 sensitive, as ouabain-sensitive Na(+)-independent ATP hydrolysis, and as 86Rb uptake was significantly higher in I than in A rats. The ratio between apically located K(+)-ATPases and basolateral Na(+)-K(+)-ATPase activities was almost 3.2-fold higher in I than in A colon. We identified with Northern blot the expression of the colonic H(+)-K(+)-ATPase and the Na(+)-K(+)-ATPase alpha-subunits. The alpha-mRNA expression of both ATPases was significantly higher in I than in A rats. The pH and K+ sensitivity of the ouabain-insensitive, SCH-28080-sensitive K(+)-ATPase was the same in I and A colons. In conclusion, the relative activity of apical K+ absorbing ATPases is higher in the I than in the A colon, which should aid infants in retaining K+.
40
SWEADNER, Kathleen J., i Claudia DONNET. "Structural similarities of Na,K-ATPase and SERCA, the Ca2+-ATPase of the sarcoplasmic reticulum". Biochemical Journal 356, nr 3 (8.06.2001): 685–704. http://dx.doi.org/10.1042/bj3560685.
Pełny tekst źródłaStreszczenie:
The crystal structure of SERCA1a (skeletal-muscle sarcoplasmic-reticulum/endoplasmic-reticulum Ca2+-ATPase) has recently been determined at 2.6 Å (note 1 Å = 0.1nm) resolution [Toyoshima, Nakasako, Nomura and Ogawa (2000) Nature (London) 405, 647–655]. Other P-type ATPases are thought to share key features of the ATP hydrolysis site and a central core of transmembrane helices. Outside of these most-conserved segments, structural similarities are less certain, and predicted transmembrane topology differs between subclasses. In the present review the homologous regions of several representative P-type ATPases are aligned with the SERCA sequence and mapped on to the SERCA structure for comparison. Homology between SERCA and the Na,K-ATPase is more extensive than with any other ATPase, even PMCA, the Ca2+-ATPase of plasma membrane. Structural features of the Na,K-ATPase are projected on to the Ca2+-ATPase crystal structure to assess the likelihood that they share the same fold. Homology extends through all ten transmembrane spans, and most insertions and deletions are predicted to be at the surface. The locations of specific residues are examined, such as proteolytic cleavage sites, intramolecular cross-linking sites, and the binding sites of certain other proteins. On the whole, the similarity supports a shared fold, with some particular exceptions.
41
Meade, John C. "P-type transport ATPases in Leishmania and Trypanosoma". Parasite 26 (2019): 69. http://dx.doi.org/10.1051/parasite/2019069.
Pełny tekst źródłaStreszczenie:
P-type ATPases are critical to the maintenance and regulation of cellular ion homeostasis and membrane lipid asymmetry due to their ability to move ions and phospholipids against a concentration gradient by utilizing the energy of ATP hydrolysis. P-type ATPases are particularly relevant in human pathogenic trypanosomatids which are exposed to abrupt and dramatic changes in their external environment during their life cycles. This review describes the complete inventory of ion-motive, P-type ATPase genes in the human pathogenic Trypanosomatidae; eight Leishmania species (L. aethiopica, L. braziliensis, L. donovani, L. infantum, L. major, L. mexicana, L. panamensis, L. tropica), Trypanosoma cruzi and three Trypanosoma brucei subspecies (Trypanosoma brucei brucei TREU927, Trypanosoma brucei Lister strain 427, Trypanosoma brucei gambiense DAL972). The P-type ATPase complement in these trypanosomatids includes the P1B (metal pumps), P2A (SERCA, sarcoplasmic-endoplasmic reticulum calcium ATPases), P2B (PMCA, plasma membrane calcium ATPases), P2D (Na+ pumps), P3A (H+ pumps), P4 (aminophospholipid translocators), and P5B (no assigned specificity) subfamilies. These subfamilies represent the P-type ATPase transport functions necessary for survival in the Trypanosomatidae as P-type ATPases for each of these seven subfamilies are found in all Leishmania and Trypanosoma species included in this analysis. These P-type ATPase subfamilies are correlated with current molecular and biochemical knowledge of their function in trypanosomatid growth, adaptation, infectivity, and survival.
42
Masuda, Claudio Akio, i Mónica Montero-Lomelí. "An NH2-terminal deleted plasma membrane H+-ATPase is a dominant negative mutant and is sequestered in endoplasmic reticulum derived structures". Biochemistry and Cell Biology 78, nr 1 (1.02.2000): 51–58. http://dx.doi.org/10.1139/o99-071.
Pełny tekst źródłaStreszczenie:
The NH2-terminus of the plasma membrane H+-ATPase is one of the least conserved segments of this protein among fungi. We constructed and expressed a mutant H+-ATPase from Saccharomyces cerevisiae deleted at an internal peptide within the cytoplasmic NH2-terminus (D44-F116). When the enzyme was subjected to limited trypsinolysis it was digested more rapidly than wild type H+-ATPase. Membrane fractionation experiments and immunofluorescence microscopy, using antibodies against H+-ATPase showed that the mutant ATPase is retained in the endoplasmic reticulum. The pattern observed in the immunofluorescence microscopy resembled structures similar to Russell bodies (modifications of the endoplasmic reticulum membranes) recently described in yeast. When the wild type H+-ATPase was co-expressed with the mutant, wild type H+-ATPase was also retained in the endoplasmic reticulum. Co-expression of both ATPases in a wild type yeast strain was lethal, demonstrating that this is a dominant negative mutant.
43
Kimura, M., Y. Yamaguchi, S. Takada i K. Tanabe. "Cloning of a Ca(2+)-ATPase gene of Plasmodium falciparum and comparison with vertebrate Ca(2+)-ATPases". Journal of Cell Science 104, nr 4 (1.04.1993): 1129–36. http://dx.doi.org/10.1242/jcs.104.4.1129.
Pełny tekst źródłaStreszczenie:
A Ca(2+)-ATPase gene was cloned from the genomic libraries of Plasmodium falciparum. From the deduced amino acid sequence of the gene, a 139 kDa protein with a total of 1228 amino acids was predicted. Sequence of a partial cDNA clone of the gene identified two introns near the 3′-end at the regions identical to the regions assumed for the Ca(2+)-ATPase gene of P. yoelii, a rodent malaria species. As compared with a variety of Ca(2+)-ATPases, the P. falciparum Ca(2+)-ATPase had the highest amino acid sequence homology (78%) to the P. yoelii Ca(2+)-ATPase, moderate homology (45-50%) to vertebrate sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases (SERCAs), and lowest homology (20%) to a plasma membrane Ca(2+)-ATPase. The P. falciparum protein conserved sequences and residues that are important for the function and/or structure of the organellar type Ca(2+)-ATPase, such as high affinity Ca(2+)-binding sites, fluorescein isothiocyanate (FITC)-binding regions, and the phosphorylation site, but the protein did not contain calmodulin-binding regions that occur in the plasma membrane type Ca(2+)-ATPase. Thus we concluded the cloned gene was the organellar type Ca(2+)-ATPase of P. falciparum. In a region between the phosphorylation site and FITC-binding region, the P. falciparum protein was about 200 residues longer than the rabbit SERCA and lacked a sequence that binds to phospholamban, a protein that regulates the activity of the rabbit SERCA.(ABSTRACT TRUNCATED AT 250 WORDS)
44
Winter, Christian, Nicole B. Kampik, Luca Vedovelli, Florina Rothenberger, Teodor G. Păunescu, Paul A. Stehberger, Dennis Brown, Hubert John i Carsten A. Wagner. "Aldosterone stimulates vacuolar H+-ATPase activity in renal acid-secretory intercalated cells mainly via a protein kinase C-dependent pathway". American Journal of Physiology-Cell Physiology 301, nr 5 (listopad 2011): C1251—C1261. http://dx.doi.org/10.1152/ajpcell.00076.2011.
Pełny tekst źródłaStreszczenie:
Urinary acidification in the collecting duct is mediated by the activity of H+-ATPases and is stimulated by various factors including angiotensin II and aldosterone. Classically, aldosterone effects are mediated via the mineralocorticoid receptor. Recently, we demonstrated a nongenomic stimulatory effect of aldosterone on H+-ATPase activity in acid-secretory intercalated cells of isolated mouse outer medullary collecting ducts (OMCD). Here we investigated the intracellular signaling cascade mediating this stimulatory effect. Aldosterone stimulated H+-ATPase activity in isolated mouse and human OMCDs. This effect was blocked by suramin, a general G protein inhibitor, and GP-2A, a specific Gαq inhibitor, whereas pertussis toxin was without effect. Inhibition of phospholipase C with U-73122, chelation of intracellular Ca2+ with BAPTA, and blockade of protein kinase C prevented the stimulation of H+-ATPases. Stimulation of PKC by DOG mimicked the effect of aldosterone on H+-ATPase activity. Similarly, aldosterone and DOG induced a rapid translocation of H+-ATPases to the luminal side of OMCD cells in vivo. In addition, PD098059, an inhibitor of ERK1/2 activation, blocked the aldosterone and DOG effects. Inhibition of PKA with H89 or KT2750 prevented and incubation with 8-bromoadenosine-cAMP mildly increased H+-ATPase activity. Thus, the nongenomic modulation of H+-ATPase activity in OMCD-intercalated cells by aldosterone involves several intracellular pathways and may be mediated by a Gαq protein-coupled receptor and PKC. PKA and cAMP appear to have a modulatory effect. The rapid nongenomic action of aldosterone may participate in the regulation of H+-ATPase activity and contribute to final urinary acidification.
45
Sennoune, Souad R., Karina Bakunts, Gloria M. Martínez, Jenny L. Chua-Tuan, Yamina Kebir, Mohamed N. Attaya i Raul Martínez-Zaguilán. "Vacuolar H+-ATPase in human breast cancer cells with distinct metastatic potential: distribution and functional activity". American Journal of Physiology-Cell Physiology 286, nr 6 (czerwiec 2004): C1443—C1452. http://dx.doi.org/10.1152/ajpcell.00407.2003.
Pełny tekst źródłaStreszczenie:
Tumor cells thrive in a hypoxic microenvironment with an acidic extracellular pH. To survive in this harsh environment, tumor cells must exhibit a dynamic cytosolic pH regulatory system. We hypothesize that vacuolar H+-ATPases (V-ATPases) that normally reside in acidic organelles are also located at the cell surface, thus regulating cytosolic pH and exacerbating the migratory ability of metastatic cells. Immunocytochemical data revealed for the first time that V-ATPase is located at the plasma membrane of human breast cancer cells: prominent in the highly metastatic and inconspicuous in the lowly metastatic cells. The V-ATPase activities in isolated plasma membranes were greater in highly than in lowly metastatic cells. The proton fluxes via V-ATPase evaluated by fluorescence spectroscopy in living cells were greater in highly than in lowly metastatic cells. Interestingly, lowly metastatic cells preferentially used the ubiquitous Na+/H+exchanger and HCO3−-based H+-transporting mechanisms, whereas highly metastatic cells used plasma membrane V-ATPases. The highly metastatic cells were more invasive and migratory than the lowly metastatic cells. V-ATPase inhibitors decreased the invasion and migration in the highly metastatic cells. Altogether, these data indicate that V-ATPases located at the plasma membrane are involved in the acquisition of a more metastatic phenotype.
46
Lin, Wenwei, Xiang Zhou, Wenxin Tang, Koji Takahashi, Xue Pan, Jiawei Dai, Hong Ren i in. "TMK-based cell-surface auxin signalling activates cell-wall acidification". Nature 599, nr 7884 (27.10.2021): 278–82. http://dx.doi.org/10.1038/s41586-021-03976-4.
Pełny tekst źródłaStreszczenie:
AbstractThe phytohormone auxin controls many processes in plants, at least in part through its regulation of cell expansion1. The acid growth hypothesis has been proposed to explain auxin-stimulated cell expansion for five decades, but the mechanism that underlies auxin-induced cell-wall acidification is poorly characterized. Auxin induces the phosphorylation and activation of the plasma membrane H+-ATPase that pumps protons into the apoplast2, yet how auxin activates its phosphorylation remains unclear. Here we show that the transmembrane kinase (TMK) auxin-signalling proteins interact with plasma membrane H+-ATPases, inducing their phosphorylation, and thereby promoting cell-wall acidification and hypocotyl cell elongation in Arabidopsis. Auxin induced interactions between TMKs and H+-ATPases in the plasma membrane within seconds, as well as TMK-dependent phosphorylation of the penultimate threonine residue on the H+-ATPases. Our genetic, biochemical and molecular evidence demonstrates that TMKs directly phosphorylate plasma membrane H+-ATPase and are required for auxin-induced H+-ATPase activation, apoplastic acidification and cell expansion. Thus, our findings reveal a crucial connection between auxin and plasma membrane H+-ATPase activation in regulating apoplastic pH changes and cell expansion through TMK-based cell surface auxin signalling.
47
Granger, D., M. Marsolais, J. Burry i R. Laprade. "V-type H+-ATPase in the human eccrine sweat duct: immunolocalization and functional demonstration". American Journal of Physiology-Cell Physiology 282, nr 6 (1.06.2002): C1454—C1460. http://dx.doi.org/10.1152/ajpcell.00319.2001.
Pełny tekst źródłaStreszczenie:
We investigated for the presence of a vacuolar-type H+-ATPase (V-ATPase) in the human eccrine sweat duct (SD). With the use of immunocytochemistry, an anti-V- ATPase antibody showed a strong staining at the apical membrane and a weaker one in the cytoplasm. Cold preservation followed by rewarming did not alter this staining pattern. With the use of the pH-sensitive dye 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein on isolated and perfused straight SD under HCO[Formula: see text]-free conditions and in the absence of Na+, proton extrusion was determined from the recovery rate of intracellular pH (dpHi/d t) following an acid load. Oligomycin (25 μM), an inhibitor of F-type ATPases, decreased dpHi/d t by 88 ± 6%, suggesting a role for an ATP-dependent process involved in pHi recovery. Moreover, dpHi/d t was inhibited at 95 ± 3% by 100 nM luminal concanamycin A, a specific inhibitor of V-ATPases, whereas 10 μM bafilomycin A1, another specific inhibitor of V-ATPases, was required to decrease dpHi/d t by 73%. These results strongly suggest that a V-ATPase is involved in proton secretion in the human eccrine SD.
48
Jaisser, Frederic, i Ahmed T. Beggah. "The nongastric H+-K+-ATPases: molecular and functional properties". American Journal of Physiology-Renal Physiology 276, nr 6 (1.06.1999): F812—F824. http://dx.doi.org/10.1152/ajprenal.1999.276.6.f812.
Pełny tekst źródłaStreszczenie:
The Na-K/H-K-ATPase gene family is divided in three subgroups including the Na-K-ATPases, mainly involved in whole body and cellular ion homeostasis, the gastric H-K-ATPase involved in gastric fluid acidification, and the newly described nongastric H-K-ATPases for which the identification of physiological roles is still in its infancy. The first member of this last subfamily was first identified in 1992, rapidly followed by the molecular cloning of several other members. The relationship between each member remains unclear. The functional properties of these H-K-ATPases have been studied after their ex vivo expression in various functional expression systems, including the Xenopus laevisoocyte, the insect Sf9 cell line, and the human HEK 293 cells. All these H-K-ATPase α-subunits appear to encode H-K-ATPases when exogenously expressed in such expression systems. Recent data suggest that these H-K-ATPases could also transport Na+ in exchange for K+, revealing a complex cation transport selectivity. Moreover, they display a unique pharmacological profile compared with the canonical Na-K-ATPases or the gastric H-K-ATPase. In addition to their molecular and functional characterizations, a major goal is to correlate the molecular expression of these cloned H-K-ATPases with the native K-ATPases activities described in vivo. This appears to be more complex than anticipated. The discrepancies between the functional data obtained by exogenous expression of the nongastric H-K-ATPases and the physiological data obtained in native organs could have several explanations as discussed in the present review. Extensive studies will be required in the future to better understand the physiological role of these H-K-ATPases, especially in disease processes including ionic or acid-base disorders.
49
Ferents, Iryna M., Solomiia V. Bychkova i Mykola A. Bychkov. "PECULIARITIES OF THE EFFECTS OF BILE ACIDS ON ATPASE ACTIVITY OF THE COLON MUCOSA IN PATIENTS WITH OVERWEIGHT AND IRRITABLE BOWEL SYNDROME". Wiadomości Lekarskie 73, nr 3 (2020): 574–77. http://dx.doi.org/10.36740/wlek202003133.
Pełny tekst źródłaStreszczenie:
The aim is to investigate the effect of bile acids on the ATPase activity of the colon mucosa in patients with overweight and irritable bowel syndrome (IBS). Materials and methods: Completely examined 12 patients with IBS and overweight.We estimated the ATPase activity of colon mucous of the patients with IBSspectrophotometrically by determined the content of orthophosphate that was released after ATP hydrolysis. We studied the effect of 3-sulphate of taurolitocholate (TLC-S) on specific activities of Na+/ K+-ATPase, Ca2+-ATPase of endoplasmatic reticulum (EPR),Ca2+-ATPase of plasmatic membrane (PM) and basal Mg2+-ATPase of postmitochondrial subcellular fraction of colon mucous of the patients with IBS. Results: We establishedthe specific activities of Na+/K+-ATPase, Ca2+-ATPase of EPR,Ca2+-ATPase of PM and basal Mg2+-ATPase. Therewere(6.06 ± 1.61), (5.88 ± 1.19), (8.86 ± 1.56) (6.44 ± 2.02)μmol Pi/ mg protein per hour, respectively. TLC-S (50 μM) did not causedany change of Na+/K+-ATPase , as well as Ca2+-ATPasesactivities, but statistically significant increased activity of Mg2+-ATPase of postmitochondrial subcellular fraction of colon mucous of the patients with IBS by 4 fold. Conclusions: TLC-S increased basal Mg2+-ATPase in the postmitochondrial fraction of colon mucous of the patients with overweight and IBS, but had no effect on Na+/K+-ATPase and Ca2+-ATPases activities. It has been suggested that activation of basal Mg2+-ATPase under by TLC-S may indicates the role of the endo-lysosomal system of epitheliocytes of colon mucous in developing of pathology IBS.
50
Asano, Shinji, Satomi Hoshina, Yumi Nakaie, Toshiyuki Watanabe, Michihiko Sato, Yuichi Suzuki i Noriaki Takeguchi. "Functional expression of putative H+-K+-ATPase from guinea pig distal colon". American Journal of Physiology-Cell Physiology 275, nr 3 (1.09.1998): C669—C674. http://dx.doi.org/10.1152/ajpcell.1998.275.3.c669.
Pełny tekst źródłaStreszczenie:
A guinea pig cDNA encoding the putative colonic H+-K+-ATPase α-subunit (T. Watanabe, M. Sato, K. Kaneko, T. Suzuki, T. Yoshida, and Y. Suzuki; GenBank accession no. D21854 ) was functionally expressed in HEK-293, a human kidney cell line. The cDNA for the putative colonic H+-K+-ATPase was cotransfected with cDNA for either rabbit gastric H+-K+-ATPase or TorpedoNa+-K+-ATPase β-subunit. In both expressions, Na+-independent, K+-dependent ATPase (K+-ATPase) activity was detected in the membrane fraction of the cells, with a Michaelis-Menten constant for K+ of 0.68 mM. The expressed K+-ATPase activity was inhibited by ouabain, with its IC50 value being 52 μM. However, the activity was resistant to Sch-28080, an inhibitor specific for gastric H+-K+-ATPase. The ATPase was not functionally expressed in the absence of the β-subunits. Therefore, it is concluded that the cDNA encodes the catalytic subunit (α-subunit) of the colonic H+-K+-ATPase. Although the β-subunit of the colonic H+-K+-ATPase has not been identified yet, both gastric H+-K+-ATPase and Na+-K+-ATPase β-subunits were found to act as a surrogate for the colonic β-subunit for the functional expression of the ATPase. The present colonic H+-K+-ATPase first expressed in mammalian cells showed the highest ouabain sensitivity in expressed colonic H+-K+-ATPases so far reported (rat colonic in Xenopus oocytes had an IC 50 = 0.4–1 mM; rat colonic in Sf9 cells had no ouabain sensitivity).