Journal articles on the topic 'Proteolysis'
To see the other types of publications on this topic, follow the link: Proteolysis.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Proteolysis.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Navegantes, Luiz Carlos C., Neusa M. Z. Resano, Renato H. Migliorini, and Isis C. Kettelhut. "Effect of guanethidine-induced adrenergic blockade on the different proteolytic systems in rat skeletal muscle." American Journal of Physiology-Endocrinology and Metabolism 277, no. 5 (November 1, 1999): E883—E889. http://dx.doi.org/10.1152/ajpendo.1999.277.5.e883.
Full textAbstract:
Overall proteolysis and the activity of skeletal muscle proteolytic systems were investigated in rats submitted to guanethidine-induced adrenergic blockade for 4 days. In soleus, overall proteolysis increased by 15–20% during the first 2 days of guanethidine treatment but decreased to levels below control values after 4 days. Extensor digitorum longus (EDL) did not show the initial increase in total proteolysis, which was already reduced after 2 days of guanethidine treatment. The initial rise in the rate of protein degradation in soleus was accompanied by an increased activity of the Ca2+-dependent proteolytic pathway. In both soleus and EDL, the reduction in overall proteolysis was paralleled by decreased activities of the Ca2+-dependent and ATP-dependent proteolytic processes. No change was observed in the activity of the lysosomal proteolytic system. Overall proteolysis in soleus and EDL from nontreated rats was partially inhibited by isoproterenol, in vitro. The data suggest an acute inhibitory control of skeletal muscle proteolysis by the adrenergic system, well evident in the oxidative muscle, with an important participation of the Ca2+-dependent pathway.
2
Navegantes, Luiz Carlos C., Neusa M. Z. Resano, Renato H. Migliorini, and Ísis C. Kettelhut. "Catecholamines inhibit Ca2+-dependent proteolysis in rat skeletal muscle through β2-adrenoceptors and cAMP." American Journal of Physiology-Endocrinology and Metabolism 281, no. 3 (September 1, 2001): E449—E454. http://dx.doi.org/10.1152/ajpendo.2001.281.3.e449.
Full textAbstract:
Overall proteolysis and the activity of skeletal muscle proteolytic systems were investigated in rats 1, 2, or 4 days after adrenodemedullation. Adrenodemedullation reduced plasma epinephrine by 95% and norepinephrine by 35% but did not affect muscle norepinephrine content. In soleus and extensor digitorum longus (EDL) muscles, rates of overall proteolysis increased by 15–20% by 2 days after surgery but returned to normal levels after 4 days. The rise in rates of protein degradation was accompanied by an increased activity of Ca2+-dependent proteolysis in both muscles, with no significant change in the activity of lysosomal and ATP-dependent proteolytic systems. In vitro rates of Ca2+-dependent proteolysis in soleus and EDL from normal rats decreased by ∼35% in the presence of either 10−5 M clenbuterol, a β2-adrenergic agonist, or epinephrine or norepinephrine. In the presence of dibutyryl cAMP, proteolysis was reduced by 62% in soleus and 34% in EDL. The data suggest that catecholamines secreted by the adrenal medulla exert an inhibitory control of Ca2+-dependent proteolysis in rat skeletal muscle, mediated by β2-adrenoceptors, with the participation of a cAMP-dependent pathway.
3
LARBAUD, Daniel, Michèle BALAGE, Daniel TAILLANDIER, Lydie COMBARET, Jean GRIZARD, and Didier ATTAIX. "Differential regulation of the lysosomal, Ca2+-dependent and ubiquitin/proteasome-dependent proteolytic pathways in fast-twitch and slow-twitch rat muscle following hyperinsulinaemia." Clinical Science 101, no. 6 (October 26, 2001): 551–58. http://dx.doi.org/10.1042/cs1010551.
Full textAbstract:
In order to characterize the poorly defined mechanisms that account for the anti-proteolytic effects of insulin in skeletal muscle, we investigated in rats the effects of a 3h systemic euglycaemic hyperinsulinaemic clamp on lysosomal, Ca2+-dependent proteolysis, and on ubiquitin/proteasome-dependent proteolysis. Proteolysis was measured in incubated fast-twitch mixed-fibre extensor digitorum longus (EDL) and slow-twitch red-fibre soleus muscles harvested at the end of insulin infusion. Insulin inhibited proteolysis (P < 0.05) in both muscles. This anti-proteolytic effect disappeared in the presence of inhibitors of the lysosomal/Ca2+-dependent proteolytic pathways in the soleus, but not in the EDL, where only the proteasome inhibitor MG 132 (benzyloxycarbonyl-leucyl-leucyl-leucinal) was effective. Furthermore, insulin depressed ubiquitin mRNA levels in the mixed-fibre tibialis anterior, but not in the red-fibre diaphragm muscle, suggesting that insulin inhibits ubiquitin/proteasome-dependent proteolysis in mixed-fibre muscles only. However, depressed ubiquitin mRNA levels in such muscles were not associated with significant decreases in the amount of ubiquitin conjugates, or in mRNA levels or protein content for the 14kDa ubiquitin-conjugating enzyme E2 and 20S proteasome subunits. Thus alternative, as yet unidentified, mechanisms are likely to contribute to inhibit the ubiquitin/proteasome system in mixed-fibre muscles.
4
Kominami, Yuri, Tatsuya Hayashi, Tetsuji Tokihiro, and Hideki Ushio. "A Novel Analysis of the Peptide Terminome Characterizes Dynamics of Proteolytic Regulation in Vertebrate Skeletal Muscle Under Severe Stress." Proteomes 7, no. 1 (February 13, 2019): 6. http://dx.doi.org/10.3390/proteomes7010006.
Full textAbstract:
In healthy cells, proteolysis is orderly executed to maintain basal homeostasis and normal physiology. Dyscontrol in proteolysis under severe stress condition induces cell death, but the dynamics of proteolytic regulation towards the critical phase remain unclear. Teleosts have been suggested an alternative model for the study of proteolysis under severe stress. In this study, horse mackerel (Trachurus japonicus) was used and exacerbated under severe stress conditions due to air exposure. Although the complete genome for T. japonicus is not available, a transcriptomic analysis was performed to construct a reference protein database, and the expression of 72 proteases were confirmed. Quantitative peptidomic analysis revealed that proteins related to glycolysis and muscle contraction systems were highly cleaved into peptides immediately under the severe stress. Novel analysis of the peptide terminome using a multiple linear regression model demonstrated profiles of proteolysis under severe stress. The results indicated a phase transition towards dyscontrol in proteolysis in T. japonicus skeletal muscle during air exposure. Our novel approach will aid in investigating the dynamics of proteolytic regulation in skeletal muscle of non-model vertebrates.
5
Portbury, Andrea L., Monte S. Willis, and Cam Patterson. "Tearin' Up My Heart: Proteolysis in the Cardiac Sarcomere." Journal of Biological Chemistry 286, no. 12 (January 21, 2011): 9929–34. http://dx.doi.org/10.1074/jbc.r110.170571.
Full textAbstract:
Proteolysis within the cardiac sarcomere is a constantly evolving area of research. Three major pathways of proteolysis have been identified as being active within the cardiac sarcomere, namely the ubiquitin-proteasome system, autophagy, and the calpain system. The role of ubiquitin-proteasome system-mediated proteolysis in cardiovascular health and disease has been known for some time; however, it is now apparent that other proteolytic systems also aid in the stabilization of cardiac sarcomere structure and function. This minireview focuses on the individual as well as cooperative involvement of each of these three major pathways of proteolysis within the cardiac sarcomere.
6
Sun, Z., W. Carpiaux, D. Fan, Y. Fan, R. Lakshminarayanan, and J. Moradian-Oldak. "Apatite Reduces Amelogenin Proteolysis by MMP-20 and KLK4 in vitro." Journal of Dental Research 89, no. 4 (February 16, 2010): 344–48. http://dx.doi.org/10.1177/0022034509360660.
Full textAbstract:
Two enamel proteases, matrix metalloproteinase-20 (MMP-20) and kallikrein 4 (KLK4), are known to cleave amelogenin and are necessary for proper enamel formation. However, the effect of hydroxyapatite (HAP) on the proteolytic activity of these enzymes remains unclear. To investigate whether apatite affects normal amelogenin proteolysis, we used 2 different isoforms of amelogenin combined with the appropriate enzymes to analyze proteolytic processing rates in the presence or absence of synthetic hydroxyapatite (HAP) crystals (N = 3). We found a distinct dose-dependent relationship between the amount of HAP present in the proteolysis mixture and the rate of rP172 degradation by rpMMP-20, whereas the effect of HAP on proteolysis of either rP172 or rP148 by rhKLK4 was less prominent.
7
Picard, Catherine, Isabelle Plard, Dominique Rongdaux-Gaida, and Jean-Claude Collin. "Detection of proteolysis in raw milk stored at low temperature by an inhibition ELISA." Journal of Dairy Research 61, no. 3 (August 1994): 395–404. http://dx.doi.org/10.1017/s0022029900030818.
Full textAbstract:
SummaryAn inhibition ELISA (enzyme-linked immunosorbent assay) was developed for the determination of caseinomacropeptide (CMP) in order to estimate the proteolysis of κ-casein due to the enzymes of psychrotrophic bacteria in bulk raw milk. The CMP present in milk was quantified specifically by an antibody. The limit of detection was ∽ 0·1 μg/ml and the CV was < 10%. This method was used to study the proteolytic activity of three strains of psychrotrophic Pseudomonas fluorescens in raw milk and to analyse different raw milk samples supplied by four dairy plants. The proteolytic activity for different strains of psychrotrophs and for different milk samples varied considerably, but no correlation was established between the level of microbial flora and κ-casein proteolysis. It is thus not possible to determine the extent of proteolysis from the bacterial count alone. However, by CMP determination in bulk raw milk samples after 6 d storage at 4°C, the mean κ-casein proteolysis was ∽ 4%. Among the milk samples analysed that contained < 107 cfu psychrotrophs/ml, 30% exhibited a proteolysis of κ-casein < 0·5%, i.e. < 5μg CMP/ml.
8
Solioz, M. "Role of proteolysis in copper homoeostasis." Biochemical Society Transactions 30, no. 4 (August 1, 2002): 688–91. http://dx.doi.org/10.1042/bst0300688.
Full textAbstract:
The cop operon of Enterococcus hirae controls cytoplasmic copper levels. It encodes two copper ATPases, a repressor, and the CopZ metallo-chaperone. Transcription of these genes is induced by copper. However, at higher copper concentrations, CopZ is degraded by a copper-activated proteolytic activity. This specific proteolysis of CopZ can also be demonstrated in vitro with E. hirae extracts. Growth of the cells in copper increases the copper-inducible proteolytic activity in extracts. Zymography reveals the presence of a copper-dependent protease in crude cell lysates. Copper-stimulated proteolysis of CopZ appears to play an important role in copper homoeostasis by E. hirae.
9
Shang, F., and A. Taylor. "Oxidative stress and recovery from oxidative stress are associated with altered ubiquitin conjugating and proteolytic activities in bovine lens epithelial cells." Biochemical Journal 307, no. 1 (April 1, 1995): 297–303. http://dx.doi.org/10.1042/bj3070297.
Full textAbstract:
Roles for ubiquitin (an 8.5 kDa polypeptide) involve its conjugation to proteins as a signal to initiate degradation and as a stress protein. We investigated ubiquitin conjugation and ubiquitin-dependent proteolytic activities in cultured bovine lens epithelial cells (BLECs) upon oxidative challenge. A 44% decrease in intracellular glutathione confirmed oxidative stress upon incubation with 1 mM H2O2. After 30 min incubation, endogenous high-molecular-mass ubiquitin conjugates decreased 73%, and intracellular proteolysis decreased about 50%. In the supernatants of the oxidatively treated BLECs, the ability to form high-molecular-mass ubiquitin conjugates with exogenous 125I-labelled ubiquitin decreased 28%, and ATP-dependent degradation of oxidized alpha-crystallin decreased 36%. When the H2O2-treated BLECs were allowed to recover for 60 min, intracellular proteolysis returned to the level of control cells. There was also a subsequent transient enhancement of intracellular proteolysis and a simultaneous recovery of endogenous high-molecular-mass ubiquitin conjugates. In parallel cell-free experiments, conjugating activity with exogenous 125I-labelled ubiquitin and ATP-dependent degradation of oxidized alpha-crystallin increased 35% and 72% respectively compared with non-oxidatively treated BLECs. ATP-independent proteolysis showed little response to exposure or removal of H2O2. These results indicate that (1) the rate of intracellular proteolysis in BLECs is associated with the level of endogenous high-molecular-mass ubiquitin conjugates and (2) oxidative stress may inactivate the ubiquitin conjugation activity with coordinate depression of proteolytic capability. Enhancement in ubiquitin conjugation and proteolytic activities during recovery from oxidative stress may be important in removal of damaged proteins and restoration of normal function of BLECs. The inactivation of ubiquitin-dependent proteolysis by oxidation may be involved in the accumulation of altered proteins and other adverse sequelae in the oxidatively challenged aging lens.
10
Mitch, William E., James L. Bailey, Xiaonan Wang, Claudine Jurkovitz, David Newby, and S. Russ Price. "Evaluation of signals activating ubiquitin-proteasome proteolysis in a model of muscle wasting." American Journal of Physiology-Cell Physiology 276, no. 5 (May 1, 1999): C1132—C1138. http://dx.doi.org/10.1152/ajpcell.1999.276.5.c1132.
Full textAbstract:
The ubiquitin-proteasome proteolytic system is stimulated in conditions causing muscle atrophy. Signals initiating this response in these conditions are unknown, although glucocorticoids are required but insufficient to stimulate muscle proteolysis in starvation, acidosis, and sepsis. To identify signals that activate this system, we studied acutely diabetic rats that had metabolic acidosis and increased corticosterone production. Protein degradation was increased 52% ( P < 0.05), and mRNA levels encoding ubiquitin-proteasome system components, including the ubiquitin-conjugating enzyme E214k, were higher (transcription of the ubiquitin and proteasome subunit C3 genes in muscle was increased by nuclear run-off assay). In diabetic rats, prevention of acidemia by oral NaHCO3 did not eliminate muscle proteolysis. Adrenalectomy blocked accelerated proteolysis and the rise in pathway mRNAs; both responses were restored by administration of a physiological dose of glucocorticoids to adrenalectomized, diabetic rats. Finally, treating diabetic rats with insulin for ≥24 h reversed muscle proteolysis and returned pathway mRNAs to control levels. Thus acidification is not necessary for these responses, but glucocorticoids and a low insulin level in tandem activate the ubiquitin-proteasome proteolytic system.
11
Franch, Harold A., Xiaonan Wang, Sira Sooparb, Nikia S. Brown, and Jie Du. "Phosphatidylinositol 3-Kinase Activity Is Required for Epidermal Growth Factor to Suppress Proteolysis." Journal of the American Society of Nephrology 13, no. 4 (April 2002): 903–9. http://dx.doi.org/10.1681/asn.v134903.
Full textAbstract:
ABSTRACT. Suppression of protein breakdown occurs commonly in cell growth, but the pathways responsible for controlling proteolysis are poorly understood. Protein breakdown in NRK-52E renal epithelial cells treated with epidermal growth factor (EGF) and intracellular signaling inhibitors or dominant negative signaling molecules contained in an adenoviral vector were measured. The tyrosine kinase inhibitor, herbimycin A, eliminated the suppression of proteolysis induced by EGF. In contrast, the Src inhibitor, PP1, had no effect. Expression of dominant negative H-RasY57 blocked the ability of EGF to stimulate downstream targets of Ras and also reduced the ability of EGF to suppress proteolysis. Inhibiting MEK did not influence the ability of EGF to suppress proteolysis, but the phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor, LY249002, stimulated basal proteolysis and completely eliminated the proteolytic response to EGF. Use of an adenovirus that expresses a dominant negative p85 subunit of class 1 PI 3-kinase completely blocked the ability of EGF to suppress proteolysis, whereas use of an adenovirus expressing a K227E constitutively active p110 subunit reproduced the reduction in protein breakdown. It was concluded that EGF suppresses proteolysis by a mechanism that involves Ras and class 1 PI 3-kinase.
12
Lockwood, Thomas D. "Redox-dependent and redox-independent subcomponents of protein degradation in perfused myocardium." American Journal of Physiology-Endocrinology and Metabolism 276, no. 5 (May 1, 1999): E945—E954. http://dx.doi.org/10.1152/ajpendo.1999.276.5.e945.
Full textAbstract:
The integration of proteolytic pathways with metabolism was investigated in perfused rat myocardium. After a 10-min incorporation period, the minute-to-minute release of [3H]leucine from myocardial proteins was measured in nonrecirculating effluent perfusate. The nontoxic pro-oxidant probe diamide (100 μM) or a supraphysiological concentration of the endogenous oxidative metabolite dehydroascorbic acid (200 μM) reversibly inhibited 75% of myocardial proteolysis consisting of several known subcomponents (redox dependent); however, 25% of proteolysis was diamide insensitive (redox independent). Decrease in extracellular glucose concentration from 10 to 0.1 mM strongly increased the potencies of minimally effective concentrations of diamide (10 μM) or dehydroascorbic acid (15 μM) by ∼10-fold to the respective potencies maximally inhibiting proteolysis. The reversal of diamide action was also strongly dependent on the perfusate glucose concentration observed at 0.1, 0.2, 1.0 and 10 mM glucose. Proteolytic inhibition caused by diamide (100 μM) was not accompanied by change in basal tissue ATP content of 5 μmol/g wet wt. Conversely, nearly lethal 60% ATP depletion caused by sodium azide (0.4 mM) was not accompanied by change in total [3H]leucine release. Results indicate that a large proteolytic subcomponent (75%) is maintained by redox chains fed by glucose; however, there is no apparent linkage of this proteolysis to short-term ATP fluctuations. A distinct major proteolytic subcomponent (25%) does not vary in response to experimental intervention in either ATP content or redox chains.
13
Christensen, M., P. Henckel, and P. P. Purslow. "Postmortem proteolysis in pork does not depend on fibre type distribution." Proceedings of the British Society of Animal Science 2001 (2001): 79. http://dx.doi.org/10.1017/s1752756200004610.
Full textAbstract:
Proteolytic degradation is known to be faster in white muscles than in red muscles (Whipple & Koohmaraie, 1992). Variation in eating quality between muscles has often been correlated to their metabolic properties, as determined by the fibre type distribution. Correlations between fibre type distribution and postmortem proteolysis could result from two possible effects: (1) Due to their inherent differences in metabolic potential, composition and content of proteolytic enzymes, fibres of some types may degrade more than others. (2) The balance of fibre types controls postmortem (p.m.) metabolic characteristics of the muscle as a whole, with all fibre types within it being equally affected. An experiment was conducted to compare the rate of postmortem proteolysis in five porcine muscles differing in fibre type distribution and to compare the rate of proteolysis in type II fibres isolated from these muscles.
14
Manfredi, L. H., D. Lustrino, J. Machado, W. A. Silveira, N. M. Zanon, L. C. Navegantes, and I. C. Kettelhut. "Adrenodemedullation activates the Ca2+-dependent proteolysis in soleus muscles from rats exposed to cold." Journal of Applied Physiology 122, no. 2 (February 1, 2017): 317–26. http://dx.doi.org/10.1152/japplphysiol.00198.2016.
Full textAbstract:
Previous studies have shown that catecholamines in vivo and in vitro inhibit the activity of Ca2+-dependent proteolysis in skeletal muscles under basal conditions. In the present study we sought to investigate the role of catecholamines in regulating the Ca2+-dependent proteolysis in soleus and extensor digitorum longus (EDL) muscles from rats acutely exposed to cold. Overall proteolysis, the activity of proteolytic systems, protein levels and gene expression of different components of the calpain system were investigated in rats submitted to adrenodemedullation (ADMX) and exposed to cold for 24 h. ADMX drastically reduced plasma epinephrine and promoted an additional increase in the overall proteolysis, which was already increased by cold exposure. The rise in the rate of protein degradation in soleus muscles from adrenodemedullated cold-exposed rats was caused by the high activity of the Ca2+-dependent proteolysis, which was associated with the generation of a 145-kDa cleaved α-fodrin fragment, a typical calpain substrate, and lower protein levels and mRNA expression of calpastatin, the endogenous calpain inhibitor. Unlike that observed for soleus muscles, the cold-induced muscle proteolysis in EDL was not affected by ADMX. In isolated soleus muscle, clenbuterol, a selective β2-adrenoceptor agonist, reduced the basal Ca2+-dependent proteolysis and completely abolished the activation of this pathway by the cholinergic agonist carbachol. These data suggest that catecholamines released from the adrenal medulla inhibit cold-induced protein breakdown in soleus, and this antiproteolytic effect on the Ca2+-dependent proteolytic system is apparently mediated through expression of calpastatin, which leads to suppression of calpain activation. NEW & NOTEWORTHY Although many effects of the sympathetic nervous system on muscle physiology are known, the role of catecholamines in skeletal muscle protein metabolism has been scarcely studied. We suggest that catecholamines released from adrenal medulla may be of particular importance for restraining the activation of the Ca2+-dependent proteolysis in soleus muscles during acute cold exposure. This finding helps us to understand the adaptive changes that occur in skeletal muscle protein metabolism during cold stress.
15
Artemyeva, K. A., E. I. Goufman, I. I. Stepanova, N. B. Tikhonova, M. N. Boltovskaya, E. A. Ponomarenko, I. M. Bogdanova, M. V. Mnikhovich, and L. M. Mikhaleva. "The level of IgG proteolytic fragments as an additional prognostic biomarker of prostate cancer." CLINICAL AND EXPERIMENTAL MORPHOLOGY 11, no. 2 (2022): 22–31. http://dx.doi.org/10.31088/cem2022.11.2.22-31.
Full textAbstract:
Introduction. Prostate cancer (PC) leads the world structure of male cancer mortality. Understanding the prognosis for PC patients is vitally important and requires diagnostic enhancements such as developing biomarker panels. The studyaimed to estimate sensitivity, specificity, and prognostic significance of the level of immunoglobulin G (IgG) proteolysis products in the blood serum depending on PC Gleason score and detect how the levels of IgG proteolytic fragments were associated with the diagnostic marker expression. Materials and methods. The study included 90 PC patients. We used the Gleason score to evaluate tumor grade. The level of the IgG proteolysis products and total prostate-specific antigen (PSA) in the serum was detected with ELISA. We performed an immunohistochemical assay with Ki-67, plasminogen-binding protein enolase-1 (ENO-1), and prostate-specific membrane antigen (PSMA). Results. ROC analysis demonstrated 100% specificity of the IgG proteolysis products test regardless of Gleason score, while the sensitivity reached 72.2%, 57.5%, 52.6%, and 46.2% for ISUP stages 1, 2, 3, and 4, respectively. An intergroup comparison showed significant differences between patient groups according to Gleason score, preoperative PSA and IgG proteolysis product serum levels and Ki-67 index. We detected a positive correlation between the level of IgG proteolysis products in the PC patients’ serum and ENO-1 expression and a negative correlation with the Gleason score and PSMA expression. Conclusion. Preoperative detection of high levels of proteolytic IgG fragments in the serum of PC patients even with low Gleason score and PSMA expression may help predict a more aggressive disease course and choose the management strategy. Keywords: prostate cancer, plasminogen activation system, proteolytic fragments of immunoglobulin G, oncomarkers
16
Zamir, Oded, Per-Olof Hasselgren, Takashi Higashiguchi, Janice A. Frederick, and Josef E. Fischer. "Tumour necrosis factor (TNF) and interleukin-1 (IL-1) induce muscle proteolysis through different mechanisms." Mediators of Inflammation 1, no. 4 (1992): 247–50. http://dx.doi.org/10.1155/s0962935192000371.
Full textAbstract:
The purpose of this study was to test the hypothesis that muscle proteolysis induced by TNF or IL-1 is mediated by glucocorticoids. Rats were treated with 300 μg kg−1of recombinant human preparations of IL-1α (rIL-1α) or TNFα (rTNFα) divided into three equal intraperitoneal doses given over 16 h. Two hours before each cytokine injection, rats were given 5 mg kg−1of the glucocorticoid receptor blocker mifepristone RU 38486, by gavage or were gavaged with the vehicle. Eighteen hours after the first cytokine injection, total and myofibrillar protein breakdown rates were determined in incubated extensor digitorum longus muscles as release of tyrosine and 3-methylhistidine, respectively. Total and myofibrillar proteolytic rates were increased following injection of rIL-1α or rTNFα. Proteolysis induced by rIL-1α was not altered by treatment with RU 38486. In contrast, the glucocorticoid receptor blocker inhibited the proteolytic effect of rTNFα. The results suggest that the proteolytic effect of TNF is mediated by glucocorticoids and that IL-1 induces muscle proteolysis through a glucocorticoid independent pathway.
17
Moazed, Bita, and M. Desautels. "Control of proteolysis by norepinephrine and insulin in brown adipocytes: role of ATP, phosphatidylinositol 3-kinase, and p70 S6K." Canadian Journal of Physiology and Pharmacology 80, no. 6 (June 1, 2002): 541–52. http://dx.doi.org/10.1139/y02-078.
Full textAbstract:
The objective of this study was to evaluate some of the mechanisms by which norepinephrine (NE) and insulin may influence protein degradation in mouse brown adipocytes differentiated in cultures. The effects of NE and insulin, alone or in combination, on three factors known to influence proteolysis (maintenance of cell ATP and 1-phosphatidylinositol 3-kinase (PI 3-kinase) and p70 ribosomal S6-kinase (p70 S6K) activities) were examined. It was proposed that NE affects proteolysis indirectly by decreasing cell ATP from activation of uncoupling protein-1 (UCP1)-dependent mitochondrial respiration. This was tested by comparing the effects of NE and fatty acids (which directly activate UCP1) on proteolysis in brown adipocytes, as well as in pre-adipocytes and 3T3-L1 adipocytes, which do not express UCP1. An inhibitory effect of insulin on proteolysis is observed in both pre-adipocytes and differentiated cells, whereas NE and exogenously added fatty acids inhibit proteolysis only in brown adipocytes. There is a linear relationship between reductions in cell ATP and proteolysis in response to increasing concentrations of NE or fatty acids. PI 3-kinase activity is required for proteolysis, because two selective inhibitors (wortmannin and LY294002) reduce proteolysis in both pre-adipocytes and differentiated cells. This effect is not additive to that of NE, which suggests they affect the same proteolytic pathway. In contrast to NE, insulin increases PI 3-kinase activity and phosphorylation of p70 S6K. Rapamycin, which prevented insulin-dependent increase in phosphorylation of p70 S6K, increases proteolysis in brown adipocytes and antagonizes the inhibitory effect of insulin on proteolysis, but not the inhibitory effect of NE. Thus, insulin inhibits proteolysis via rapamycin-sensitive activation of p70 S6K, whereas the effect of NE appears largely to be a function of decreasing cell ATP content.Key words: brown fat, 3T3-L1 adipocytes, protein degradation, ATP, uncoupling protein-1, fatty acids, rapamycin, wortmannin, LY294002.
18
Fagan, J. M., and A. L. Goldberg. "The rate of protein degradation in isolated skeletal muscle does not correlate with reduction-oxidation status." Biochemical Journal 227, no. 3 (May 1, 1985): 689–94. http://dx.doi.org/10.1042/bj2270689.
Full textAbstract:
It has been suggested that the cytoplasmic reduction-oxidation state correlates with, and may regulate, rates of protein breakdown in skeletal muscle. To test whether an increased lactate/pyruvate ratio is in fact generally associated with low proteolytic rates, this ratio was measured in rat extensor digitorum longus muscles incubated under conditions that rates of protein breakdown. Treatment with the calcium ionophore A23187 caused similar large increases in the lactate/pyruvate ratio at 2 microM, where proteolysis did not change, and at 20 microM, where proteolysis was greatly accelerated. Omission of Ca2+ from the medium slowed proteolysis, but decreased the lactate/pyruvate ratio. In muscles incubated at 40 degrees C, rates of proteolysis were faster, but the lactate/pyruvate ratios were higher than 37 degrees C. Thus alterations in the redox status do not necessarily correlate with, and can occur independently of, changes in proteolysis. Furthermore, insulin and inhibitors of lysosomal proteinases decreased proteolysis but, in contrast with previous reports, failed to alter the lactate/pyruvate ratio. In addition, protein breakdown decreased in muscles maintained under tension, although redox state did not change. Thus protein degradation can fall without a concomitant change in the reduction-oxidation state.
19
TAILLANDIER, Daniel, Eveline AUROUSSEAU, Dominique MEYNIAL-DENIS, Daniel BECHET, Marc FERRARA, Patrick COTTIN, André DUCASTAING, et al. "Coordinate activation of lysosomal, Ca2+-activated and ATP-ubiquitin-dependent proteinases in the unweighted rat soleus muscle." Biochemical Journal 316, no. 1 (May 15, 1996): 65–72. http://dx.doi.org/10.1042/bj3160065.
Full textAbstract:
Nine days of hindlimb suspension resulted in atrophy (55%) and loss of protein (53%) in rat soleus muscle due to a marked elevation in protein breakdown (66%, P < 0.005). To define which proteolytic system(s) contributed to this increase, soleus muscles from unweighted rats were incubated in the presence of proteolytic inhibitors. An increase in lysosomal and Ca2+-activated proteolysis (254%, P < 0.05) occurred in the atrophying incubated muscles. In agreement with the measurements in vitro, cathepsin B, cathepsins B+L and m-calpain enzyme activities increased by 111%, 92% and 180% (P < 0.005) respectively in the atrophying muscles. Enhanced mRNA levels for these proteinases (P < 0.05 to P < 0.001) paralleled the increased enzyme activities, suggesting a transcriptional regulation of these enzymes. However, the lysosomal and Ca2+-dependent proteolytic pathways accounted for a minor part of total proteolysis in both control (9%) and unweighted rats (18%). Furthermore the inhibition of these pathways failed to suppress increased protein breakdown in unweighted muscle. Thus a non-lysosomal Ca2+-independent proteolytic process essentially accounted for the increased proteolysis and subsequent muscle wasting. Increased mRNA levels for ubiquitin, the 14 kDa ubiquitin-conjugating enzyme E2 (involved in the ubiquitylation of protein substrates) and the C2 and C9 subunits of the 20 S proteasome (i.e. the proteolytic core of the 26 S proteasome that degrades ubiquitin conjugates) were observed in the atrophying muscles (P < 0.02 to P < 0.001). Analysis of C9 mRNA in polyribosomes showed equal distribution into both translationally active and inactive mRNA pools, in either unweighted or control rats. These results suggest that increased ATP-ubiquitin-dependent proteolysis is most probably responsible for muscle wasting in the unweighted soleus muscle.
20
Barrett, E. J., L. A. Jahn, D. M. Oliveras, and D. A. Fryburg. "Chloroquine does not exert insulin-like actions on human forearm muscle metabolism." American Journal of Physiology-Endocrinology and Metabolism 268, no. 5 (May 1, 1995): E820—E824. http://dx.doi.org/10.1152/ajpendo.1995.268.5.e820.
Full textAbstract:
Insulin's anabolic action on skeletal muscle and whole body protein is attributable to its action to slow tissue proteolysis. The antimalarial chloroquine inhibits lysosomal proteolysis and is reported to improve glycemia in poorly controlled diabetic patients. We infused chloroquine into the brachial artery of seven healthy postabsorptive volunteers over 3 h during a steady-state infusion of L-[ring-2,6-3H]phenylalanine (Phe) to study its effect on muscle glucose and protein turnover. Compared with basal, chloroquine increased forearm blood flow (P < 0.01) but did not change glucose uptake or lactate release. Neither Phe released from muscle by proteolysis (78 +/- 15 vs. 94 +/- 16 nmol Phe.min-1.100 ml-1) nor Phe balance (-37 +/- 7 vs. -50 +/- 6 nmol.min-1.100 ml-1) was reduced from basal. We conclude that in postabsorptive human skeletal muscle: 1) lysosomal proteolysis does not make a major contribution to proteolysis; and 2) chloroquine does not cause an acute increase in glucose uptake. These findings suggest that the inhibition of postabsorptive muscle protein degradation provoked by physiological increases in plasma insulin is likely mediated by a nonlysosomal proteolytic pathway.
21
Mahmoud, Samar A., and Peter Chien. "Regulated Proteolysis in Bacteria." Annual Review of Biochemistry 87, no. 1 (June 20, 2018): 677–96. http://dx.doi.org/10.1146/annurev-biochem-062917-012848.
Full textAbstract:
Regulated proteolysis is a vital process that affects all living things. Bacteria use energy-dependent AAA+ proteases to power degradation of misfolded and native regulatory proteins. Given that proteolysis is an irreversible event, specificity and selectivity in degrading substrates are key. Specificity is often augmented through the use of adaptors that modify the inherent specificity of the proteolytic machinery. Regulated protein degradation is intricately linked to quality control, cell-cycle progression, and physiological transitions. In this review, we highlight recent work that has shed light on our understanding of regulated proteolysis in bacteria. We discuss the role AAA+ proteases play during balanced growth as well as how these proteases are deployed during changes in growth. We present examples of how protease selectivity can be controlled in increasingly complex ways. Finally, we describe how coupling a core recognition determinant to one or more modifying agents is a general theme for regulated protein degradation.
22
Mañas-García, Laura, Charlotte Denhard, Javier Mateu, Xavier Duran, Joaquim Gea, and Esther Barreiro. "Beneficial Effects of Resveratrol in Mouse Gastrocnemius: A Hint to Muscle Phenotype and Proteolysis." Cells 10, no. 9 (September 15, 2021): 2436. http://dx.doi.org/10.3390/cells10092436.
Full textAbstract:
We hypothesized that the phenolic compound resveratrol mitigates muscle protein degradation and loss and improves muscle fiber cross-sectional area (CSA) in gastrocnemius of mice exposed to unloading (7dI). In gastrocnemius of mice (female C57BL/6J, 10 weeks) exposed to a seven-day period of hindlimb immobilization with/without resveratrol treatment, markers of muscle proteolysis (tyrosine release, systemic troponin-I), atrophy signaling pathways, and muscle phenotypic features and function were analyzed. In gastrocnemius of unloaded mice treated with resveratrol, body and muscle weight and function were attenuated, whereas muscle proteolysis (tyrosine release), proteolytic and apoptotic markers, atrophy signaling pathways, and myofiber CSA significantly improved. Resveratrol treatment of mice exposed to a seven-day period of unloading prevented body and muscle weight and limb strength loss, while an improvement in muscle proteolysis, proteolytic markers, atrophy signaling pathways, apoptosis, and muscle fiber CSA was observed in the gastrocnemius muscle. These findings may have potential therapeutic implications in the management of disuse muscle atrophy in clinical settings.
23
van de Winkel, J. G., R. van Ommen, T. W. Huizinga, M. A. de Raad, W. B. Tuijnman, P. J. Groenen, P. J. Capel, R. A. Koene, and W. J. Tax. "Proteolysis induces increased binding affinity of the monocyte type II FcR for human IgG." Journal of Immunology 143, no. 2 (July 15, 1989): 571–78. http://dx.doi.org/10.4049/jimmunol.143.2.571.
Full textAbstract:
Abstract Human monocytes express two types of IgG FcR, Fc gamma RI and Fc gamma RII. These can be assayed by using indicator E sensitized by human IgG (EA-human IgG) or mouse IgG1, (EA-mouse IgG1), respectively. On mouse macrophages, Fc gamma RI is sensitive to trypsin, whereas Fc gamma RII is trypsin resistant. We studied the effects of the proteolytic enzymes pronase and trypsin on human monocyte Fc gamma R. Neither enzyme caused a decrease in rosetting mediated by monocyte Fc gamma RI. Human Fc gamma RII is polymorphic, and monocytes interact either strongly or weakly with mouse IgG1. The interaction of low responder monocytes with mouse IgG1 was dramatically increased (to the level exhibited by high responder monocytes) by protease treatment. The effects of proteases on Fc gamma RII were investigated in more detail by using monocytes from which Fc gamma RI was selectively modulated by using immobilized immune complexes. Proteolysis of such modulated monocytes induced an increased interaction with EA-human IgG. Fc gamma RII appears to mediate this interaction. This conclusion is supported by the observation that after proteolysis, the Fc gamma RII-mediated binding of EA-mouse IgG1 becomes susceptible to inhibition by (monomeric) human IgG. To quantify the effect of proteolytic enzymes on Fc gamma RII, we performed binding studies with cell line K562, that expresses only Fc gamma RII. A significant increase in Ka of Fc gamma RII for dimeric human IgG complexes was observed when K562 cells were treated with protease. To elucidate the mechanism of this enhancement of Ka by proteolysis, we performed immunoprecipitation studies. Neither m.w., nor IEF pattern of Fc gamma RII were influenced by proteolysis. Moreover, the expression of Fc gamma RII was not affected by proteolysis as evidenced by immunofluorescence studies and Scatchard analysis, and neither were Fc gamma RI or Fc gamma RIII induced. We conclude that proteolysis increases the affinity of Fc gamma RII for human IgG, and speculate that such a proteolysis-induced change may also occur in vivo, e.g., at inflammatory sites.
24
Myagkonosov, D. S., I. T. Smykov, D. V. Abramov, and I. N. Delitskaya. "Influence of different types of fermentation-produced chymosin on quality of soft cheeses." IOP Conference Series: Earth and Environmental Science 1052, no. 1 (July 1, 2022): 012076. http://dx.doi.org/10.1088/1755-1315/1052/1/012076.
Full textAbstract:
Abstract The disadvantage of soft cheeses is their short shelf life. In soft cheeses with a high moisture content, proteolysis occurs at a high rate, as a result of which the cheeses quickly overripe. The main proteolytic agent in soft cheeses is the milk-clotting enzyme (MCE). Increasing the shelf life of cheeses can be achieved by using MCE types having low proteolytic activity (PA). We have studied the effect of MCE based on different types of fermentation-produced chymosin: Chy-max® Extra (bovine chymosin), Chy-max® M (camel chymosin), Chy-max® Supreme (“modified” chymosin) on the dynamics of proteolysis in soft cheeses and related changes in the structure of cheeses during their storage. All 3 types of studied MCEs have different levels of nonspecific PA. The higher the level of nonspecific PA of the used MCE, the higher the rate of the proteolysis process in the resulting cheeses. Increasing the dose of MCE also increases the rate of proteolysis in cheeses. To increase the shelf life of soft cheeses, which depends on the period of preservation of a dense consistency, it is promising to use MCE with low PA based on camel chymosin (Chy-max® M) and “modified” chymosin (Chy-max® Supreme).
25
TOURNU, Cécile, Alain OBLED, Marie-Paule ROUX, Marc FERRARA, Satoshi OMURA, and Daniel M. BÉCHET. "Glucose regulates protein catabolism in ras-transformed fibroblasts through a lysosomal-dependent proteolytic pathway." Biochemical Journal 357, no. 1 (June 25, 2001): 255–61. http://dx.doi.org/10.1042/bj3570255.
Full textAbstract:
Transformed cells are exposed to heterogeneous microenvironments, including low d-glucose (Glc) concentrations inside tumours. The regulation of protein turnover is commonly impaired in many types of transformed cells, but the role of Glc in this regulation is unknown. In the present study we demonstrate that Glc controls protein turnover in ras-transformed fibroblasts (KBALB). The regulation by Glc of protein breakdown was correlated with modifications in the levels of lysosomal cathepsins B, L and D, while autophagic sequestration and non-lysosomal proteolytic systems (m- and μ-calpains and the zeta-subunit of the proteasome) remained unaffected. Lactacystin, a selective inhibitor of the proteasome, depressed proteolysis, but did not prevent its regulation by Glc. The sole inhibition of the cysteine endopeptidases (cathepsins B and L, and calpains) by E-64d [(2S,3S)-trans-epoxysuccinyl-l-leucylamido-3-methylbutane ethyl ester] was also not sufficient to alter the effect of Glc on proteolysis. The Glc-dependent increase in proteolysis was, however, prevented after optimal inhibition of lysosomal cysteine and aspartic endopeptidases by methylamine. We conclude that, in transformed cells, Glc plays a critical role in the regulation of protein turnover and that the lysosomal proteolytic capacity is mainly responsible for the control of intracellular proteolysis by Glc.
26
Lavatelli, Francesca, Giulia Mazzini, Stefano Ricagno, Federica Iavarone, Paola Rognoni, Paolo Milani, Mario Nuvolone, et al. "Mass spectrometry characterization of light chain fragmentation sites in cardiac AL amyloidosis: insights into the timing of proteolysis." Journal of Biological Chemistry 295, no. 49 (September 20, 2020): 16572–84. http://dx.doi.org/10.1074/jbc.ra120.013461.
Full textAbstract:
Amyloid fibrils are polymeric structures originating from aggregation of misfolded proteins. In vivo, proteolysis may modulate amyloidogenesis and fibril stability. In light chain (AL) amyloidosis, fragmented light chains (LCs) are abundant components of amyloid deposits; however, site and timing of proteolysis are debated. Identification of the N and C termini of LC fragments is instrumental to understanding involved processes and enzymes. We investigated the N and C terminome of the LC proteoforms in fibrils extracted from the hearts of two AL cardiomyopathy patients, using a proteomic approach based on derivatization of N- and C-terminal residues, followed by mapping of fragmentation sites on the structures of native and fibrillar relevant LCs. We provide the first high-specificity map of proteolytic cleavages in natural AL amyloid. Proteolysis occurs both on the LC variable and constant domains, generating a complex fragmentation pattern. The structural analysis indicates extensive remodeling by multiple proteases, largely taking place on poorly folded regions of the fibril surfaces. This study adds novel important knowledge on amyloid LC processing: although our data do not exclude that proteolysis of native LC dimers may destabilize their structure and favor fibril formation, the data show that LC deposition largely precedes the proteolytic events documentable in mature AL fibrils.
27
Hutton, D. A., J. P. Pearson, A. Allen, and S. N. E. Foster. "Mucolysis of the colonic mucus barrier by faecal proteinases: Inhibition by interacting polyacrylate." Clinical Science 78, no. 3 (March 1, 1990): 265–71. http://dx.doi.org/10.1042/cs0780265.
Full textAbstract:
1. Mucolytic (mucus solubilizing) activity in human faeces has been characterized with both purified human and pig colonic mucin and shown to be mediated by proteolysis. 2. Mucolytic activity was demonstrated by: (i) a drop in mucin viscosity; (ii) a substantial reduction in mucin size, from polymer to degraded subunit, as assessed by Sepharose CL-2B gel filtration; (iii) formation of new N-terminal peptides. 3. Mucolytic activity was also followed in faecal extracts by its proteolytic activity using standard succinyl albumin substrate. Proteolysis extended over the pH range 4.5–11.0. Proteolysis was inhibited at pH 7.5 by soybean trypsin inhibitor and phenylmethanesulphonyl fluoride, suggesting the presence of serine proteinases. 4. The polyacrylate carbomer (934P) inhibited both mucolysis of pig colonic mucin and proteolysis of succinyl albumin. 5. Interaction between the polyacrylate (carbomer 934P) and purified human and pig colonic mucin was demonstrated by a marked synergistic increase in solution viscosity (360% above control). 6. The results demonstrate the presence of a mucolytic activity in the human colonic lumen that has the potential to degrade the mucus barrier, and that polyacrylates inhibit this mucolysis and interact to strengthen the colonic mucus barrier. Polyacrylates may therefore have therapeutic potential in inflammatory bowel disease where luminal proteolytic activity can be raised.
28
Ewald, S. J., and P. H. Refling. "Co-immunoprecipitation of the Ly-5 molecule and an endogenous protease: a proteolytic system requiring a reducing agent and Ca2+1." Journal of Immunology 134, no. 4 (April 1, 1985): 2513–19. http://dx.doi.org/10.4049/jimmunol.134.4.2513.
Full textAbstract:
Abstract Sodium [3H]borohydride- and [35S]methionine-labeled Ly-5 molecules from mouse thymocytes and T lymphoma cells were isolated with specific antibody and Staphylococcus aureus Cowan I (SaCI) strain; after extensive washing of the complexes, elution with Laemmli's reducing buffer (0.05 M Tris [pH 6.8 or 6.0], 4% sodium dodecyl sulfate [SDS], and 2% 2-mercaptoethanol [2-ME]) resulted in partial breakdown of the isolated Ly-5 molecules from a Mr = 175,000 to 150,000. Other proteins present during the elution step showed no evidence of proteolysis. 2-ME and SDS were required for proteolysis; although addition of exogenous Ca2+ during elution was not necessary, both EDTA and EGTA inhibited breakdown of the molecule that could be overcome by excess Ca2+. Of a variety of protease inhibitors and thiol-reactive agents tested, only TAME and oxidized glutathione blocked proteolysis almost completely. SaCI, serum, and contaminating antibodies were ruled out as the source of the proteolytic activity. More stringent preclearing and washing conditions did not eliminate endogenous proteolysis of the Ly-5 molecule. The endogenous proteolytic fragment had a Mr distinct from the tryptic fragment of the Ly-5 molecule. We conclude that the Ly-5 molecule may be autolytic or tightly associated with a distinct cellular protease.
29
Baracos, V. E., C. DeVivo, D. H. Hoyle, and A. L. Goldberg. "Activation of the ATP-ubiquitin-proteasome pathway in skeletal muscle of cachectic rats bearing a hepatoma." American Journal of Physiology-Endocrinology and Metabolism 268, no. 5 (May 1, 1995): E996—E1006. http://dx.doi.org/10.1152/ajpendo.1995.268.5.e996.
Full textAbstract:
Rats implanted with Yoshida ascites hepatoma (YAH) show a rapid and selective loss of muscle protein due mainly to a marked increase (63-95%) in the rate of protein degradation (compared with rates in muscles of pair-fed controls). To define which proteolytic pathways contribute to this increase, epitrochlearis muscles from YAH-bearing and control rats were incubated under conditions that modify different proteolytic systems. Overall proteolysis in either group of rats was not affected by removal of Ca2+ or by blocking the Ca(2+)-dependent proteolytic system. Inhibition of lysosomal function with methylamine reduced proteolysis (-12%) in muscles from YAH-bearing rats, but not in muscles of pair-fed rats. When ATP production was also inhibited, the remaining accelerated proteolysis in muscles of tumor-bearing rats fell to control levels. Muscles of YAH-bearing rats showed increased levels of ubiquitin-conjugated proteins and a 27-kDa proteasome subunit in Western blot analysis. Levels of mRNA encoding components of proteolytic systems were quantitated using Northern hybridization analysis. Although their total RNA content decreased 20-38%, pale muscles of YAH-bearing rats showed increased levels of ubiquitin mRNA (590-880%) and mRNA for multiple subunits of the proteasome (100-215%). Liver, kidney, heart, and brain showed no weight loss and no change in these mRNA species. Muscles of YAH-bearing rats also showed small increases (30-40%) in mRNA for cathepsins B and D, but not for calpain I or heat shock protein 70. Our findings suggest that accelerated muscle proteolysis and muscle wasting in tumor-bearing rats result primarily from activation of the ATP-dependent pathway involving ubiquitin and the proteasome.
30
Baracos, V., R. E. Greenberg, and A. L. Goldberg. "Influence of calcium and other divalent cations on protein turnover in rat skeletal muscle." American Journal of Physiology-Endocrinology and Metabolism 250, no. 6 (June 1, 1986): E702—E710. http://dx.doi.org/10.1152/ajpendo.1986.250.6.e702.
Full textAbstract:
When rat muscles were incubated in Ca2+-free media, their rates of protein break-down were significantly lower than in complete medium (2.58 mM Ca2+). Dantrolene and 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester, inhibitors of Ca2+ release from the sarcoplasmic reticulum, also reduced muscle proteolysis. When Ca2+ was added (up to 5.16 mM), proteolysis increased progressively up to 70% in the intact soleus and extensor digitorum longus muscles and up to 300% in the cut diaphragm preparation. Addition of Ca2+ did not affect the muscles' ATP or phosphocreatine content and increased protein synthesis slightly or not at all. Sr2+, Ba2+, and Mn2+ also increased proteolysis, but were less effective than Ca2+. Mg2+ inhibited the enhancement of proteolysis by Ca2+. This stimulation by Ca2+ was not affected by inhibitors of voltage-dependent Ca2+ channels, calmodulin, metalloendoproteases, microfilament or microtubule formation, or mersalyl. High Ca2+ levels also increased prostaglandin (PG) E2 production, although a rise in PGE2 did not appear essential for the increased proteolysis. The proteolysis induced by Ca2+ was prevented in muscles treated with Ep-475 or leupeptin. By contrast, these inhibitors of thiol proteases did not affect protein breakdown in Ca2+-free medium. Thus extracellular Ca2+ activates and Mg2+ inhibits a proteolytic pathway involving thiol proteases.
31
Maupin-Furlow, Julie A. "Proteolytic systems of archaea: slicing, dicing, and mincing in the extreme." Emerging Topics in Life Sciences 2, no. 4 (November 14, 2018): 561–80. http://dx.doi.org/10.1042/etls20180025.
Full textAbstract:
Archaea are phylogenetically distinct from bacteria, and some of their proteolytic systems reflect this distinction. Here, the current knowledge of archaeal proteolysis is reviewed as it relates to protein metabolism, protein homeostasis, and cellular regulation including targeted proteolysis by proteasomes associated with AAA-ATPase networks and ubiquitin-like modification. Proteases and peptidases that facilitate the recycling of peptides to amino acids as well as membrane-associated and integral membrane proteases are also reviewed.
32
Rivera, G. M., and J. E. Fortune. "Selection of the Dominant Follicle and Insulin-Like Growth Factor (IGF)-Binding Proteins: Evidence that Pregnancy-Associated Plasma Protein A Contributes to Proteolysis of IGF-Binding Protein 5 in Bovine Follicular Fluid." Endocrinology 144, no. 2 (February 1, 2003): 437–46. http://dx.doi.org/10.1210/en.2002-220657.
Full textAbstract:
Development of a dominant follicle is associated with decreased intrafollicular low molecular weight IGF-binding proteins (namely IGFBP-2, -4, and -5) and increased proteolysis of IGFBP-4 by pregnancy-associated plasma protein A (PAPP-A). In addition to IGFBP-4 proteolytic activity, bovine follicular fluid contains strong proteolytic activity for IGFBP-5, but not for IGFBP-2. Here we show that the IGFBP-5 protease present in bovine follicular fluid is a neutral/basic pH-favoring, Zn2+ metalloprotease very similar to the previously described IGFBP-4 protease. We hypothesized that immunoneutralization and immunoprecipitation with anti-PAPP-A antibodies would result in abrogation of the IGFBP-4, but not the IGFBP-5, proteolytic activity in follicular fluid. As expected, anti-PAPP-A antibodies were able to neutralize and precipitate the IGFBP-4, but not the IGFBP-5, proteolytic activity of human pregnancy serum, which was used as a positive control for PAPP-A. Surprisingly, immunoneutralization and immunoprecipitation of follicular fluid from bovine preovulatory follicles with anti-PAPP-A antibodies abrogated both IGFBP-4 and IGFBP-5 proteolysis. Quantitative results derived from phosphorimaging revealed a complete inhibition of both IGFBP-4 and -5 proteolysis by follicular fluid incubated for 2 or 5 h in the presence of anti-PAPP-A antibodies. After 18 h of incubation, anti-PAPP-A antibodies still inhibited IGFBP-5 degradation, although with an efficiency lower than that for IGFBP-4 degradation. Both proteolytic activities have identical electrophoretic mobility, and a single band (∼400 kDa) was detected by Western immunoblotting of bovine follicular fluid with anti-PAPP-A antibodies. Proteolysis of IGFBP-5 was readily detectable in follicular fluid from dominant follicles and was negligible in subordinate follicles from the same cohort. These results suggest that an active intrafollicular IGFBP-4/-5 proteolytic system, in which PAPP-A is the major protease involved, is an important determinant of follicular fate.
33
SIVANANDAM, Arun S., Subburaman MOHAN, Hirohito KITA, Sanjay KAPUR, Shin-Tai CHEN, Thomas A. LINKHART, Gyorgy BAGI, David J. BAYLINK, and Xuezhong QIN. "Studies on regulation of IGF (insulin-like growth factor)-binding protein (IGFBP) 4 proteolysis by pregnancy-associated plasma protein-A (PAPP-A) in cells treated with phorbol ester." Biochemical Journal 379, no. 1 (April 1, 2004): 57–64. http://dx.doi.org/10.1042/bj20030937.
Full textAbstract:
PAPP-A (pregnancy-associated plasma protein-A) is produced by hSFs (human skin fibroblasts) and hOBs (human osteoblasts) and enhances the mitogenic activity of IGFs (insulin-like growth factors) by degradation of IGFBP-4 (insulin-like growth factor-binding protein 4). PKC (protein kinase C) activation in these cells led to reduction in IGFBP-4 proteolysis. This study was undertaken to determine the mechanism by which activation of PKC suppresses IGFBP-4 proteolysis. Treatment of hSFs/hOBs with TPA (PMA; 100 nM) reduced IGFBP-4 proteolysis without significantly decreasing the PAPP-A level in the CM (conditioned medium). Immunodepletion of the proform of eosinophil major basic protein (proMBP), a known PAPP-A inhibitor, from CM of TPA-treated cells (TPA CM) failed to increase IGFBP-4 proteolytic activity. Transduction of hSFs with proMBP retrovirus increased the concentration of proMBP up to 30 ng/ml and led to a moderate reduction in IGFBP-4 proteolysis. In contrast, TPA treatment blocked IGFBP-4 proteolysis but failed to induce a detectable amount of proMBP in the CM. While proMBP overexpression led to the formation of a covalent proMBP–PAPP-A complex and reduced the migration of PAPP-A on SDS/PAGE, TPA treatment dose- and time-dependently increased the conversion of a ≈470 kDa PAPP-A form (PAPP-A470) to a ≈400 kDa PAPP-A form (PAPP-A400). Since unreduced PAPP-A400 co-migrated with the 400 kDa recombinant PAPP-A homodimer and since PAPP-A monomers from reduced PAPP-A470 and PAPP-A400 co-migrated on SDS/PAGE, conversion of PAPP-A470 to PAPP-A400 is unlikely to be caused by proteolytic cleavage of PAPP-A. Consistent with the data showing that the increase in the ratio of PAPP-A400/PAPP-A470 is correlated with the extent of reduction in IGFBP-4 proteolysis, partially purified PAPP-A400 exhibited a 4-fold reduction in IGFBP-4 proteolytic activity compared with PAPP-A470. These data suggest that a novel mechanism, namely conversion of PAPP-A470 to the less-active PAPP-A400, could account for the TPA-induced suppression of PAPP-A activity.
34
Scolari, G., M. Vescovo, P. G. Sarra, and V. Bottazzi. "Proteolysis in cheese made with liposome-entrapped proteolytic enzymes." Le Lait 73, no. 3 (1993): 281–92. http://dx.doi.org/10.1051/lait:1993326.
Full text
35
Kudryashova, I. V. "Proteolysis and proteolytic enzymes in structural plasticity of synapses." Neurochemical Journal 3, no. 3 (September 2009): 164–72. http://dx.doi.org/10.1134/s1819712409030027.
Full text
36
Germain, D., J. Hendley, and B. Futcher. "DNA damage inhibits proteolysis of the B-type cyclin Clb5 in S. cerevisiae." Journal of Cell Science 110, no. 15 (August 1, 1997): 1813–20. http://dx.doi.org/10.1242/jcs.110.15.1813.
Full textAbstract:
Cell cycle progression is mediated by waves of specific cyclin dependent kinases (CDKs) in all eukaryotes. Cyclins are degraded by the ubiquitin pathway of proteolysis. The recent identification of several components of the cyclin proteolysis machinery has highlighted both the importance of proteolysis at multiple transition points in the cell cycle and the involvement of other substrates degraded by the same machinery. In this study, we have investigated the effects of DNA damage on the cyclin proteolytic machinery in Saccharomyces cerevisiae. We find that the half-life of the B-type cyclin Clb5 is markedly increased following DNA damage while that of G1 cyclins is not. This effect is independent of cell cycle phase. Clb5 turnover requires p34CDC28 activity. Stabilisation of Clb5 correlates with an increase in tyrosine phosphorylation of p34CDC28, but stabilisation does not require this tyrosine phosphorylation. The stabilisation is independent of the checkpoint genes Mec1 and Rad53. These observations establish a new link between the regulation of proteolysis and DNA damage.
37
Fontana, Angelo, Patrizia Polverino De Laureto, Barbara Spolaore, Erica Frare, Paola Picotti, and Marcello Zambonin. "Probing protein structure by limited proteolysis." Acta Biochimica Polonica 51, no. 2 (June 30, 2004): 299–321. http://dx.doi.org/10.18388/abp.2004_3573.
Full textAbstract:
Limited proteolysis experiments can be successfully used to probe conformational features of proteins. In a number of studies it has been demonstrated that the sites of limited proteolysis along the polypeptide chain of a protein are characterized by enhanced backbone flexibility, implying that proteolytic probes can pinpoint the sites of local unfolding in a protein chain. Limited proteolysis was used to analyze the partly folded (molten globule) states of several proteins, such as apomyoglobin, alpha-lactalbumin, calcium-binding lysozymes, cytochrome c and human growth hormone. These proteins were induced to acquire the molten globule state under specific solvent conditions, such as low pH. In general, the protein conformational features deduced from limited proteolysis experiments nicely correlate with those deriving from other biophysical and spectroscopic techniques. Limited proteolysis is also most useful for isolating protein fragments that can fold autonomously and thus behave as protein domains. Moreover, the technique can be used to identify and prepare protein fragments that are able to associate into a native-like and often functional protein complex. Overall, our results underscore the utility of the limited proteolysis approach for unravelling molecular features of proteins and appear to prompt its systematic use as a simple first step in the elucidation of structure-dynamics-function relationships of a novel and rare protein, especially if available in minute amounts.
38
Tawa, N. E., I. C. Kettelhut, and A. L. Goldberg. "Dietary protein deficiency reduces lysosomal and nonlysosomal ATP-dependent proteolysis in muscle." American Journal of Physiology-Endocrinology and Metabolism 263, no. 2 (August 1, 1992): E326—E334. http://dx.doi.org/10.1152/ajpendo.1992.263.2.e326.
Full textAbstract:
When rats are fed a protein deficient (PD) diet for 7 days, rates of proteolysis in skeletal muscle decrease by 40-50% (N. E. Tawa, Jr., and A. L. Goldberg. Am. J. Physiol. 263 (Endocrinol. Metab. 26): E317-325, 1992). To identify the underlying biochemical adaptations, we measured different proteolytic processes in incubated muscles. The capacity for intralysosomal proteolysis, as shown by sensitivity to methylamine or lysosomal protease inhibitors, fell 55-75% in muscles from PD rats. Furthermore, extracts of muscles of PD rats showed 30-70% lower activity of many lysosomal proteases, including cathepsins B, H, and C, and carboxypeptidases A and C, as well as other lysosomal hydrolases. The fall in cathepsin B and proteolysis was evident by 3 days on the PD diet, and both returned to control levels 3 days after refeeding of the normal diet. In muscles maintained under optimal conditions, 80-90% of protein breakdown occurs by nonlysosomal pathways. In muscles of PD rats, this ATP-dependent process was also 40-60% slower. Even though overall proteolysis decreased in muscles of PD rats, their capacity for Ca(2+)-dependent proteolysis increased (by 66%), as did the activity of the calpains (+150-250%). Thus the lysosomal and the ATP-dependent processes decrease coordinately and contribute to the fall in muscle proteolysis in PD animals.
39
Li, Anguo, and Tze-Chein Wun. "Proteolysis of Tissue Factor Pathway Inhibitor (TFPI) by Plasmin: Effect on TFPI Activity." Thrombosis and Haemostasis 80, no. 09 (1998): 423–27. http://dx.doi.org/10.1055/s-0037-1615224.
Full textAbstract:
SummaryAn important regulator of the initiation of blood coagulation is the plasma glycoprotein, tissue factor pathway inhibitor (TFPI). TFPI inhibits factor Xa and factor VIIa/tissue factor complex, thereby dampens the proteolytic cascade of the tissue factor pathway. Plasma clot lysis is primarily mediated by the fibrinolytic enzyme, plasmin, which is generated through limited proteolysis of plasminogen by endogenous or exogenously administered plaminogen activators. In this study, the interaction of plasmin with recombinant E. coli-derived TFPI (rTFPI) was examined. Plasmin was found to cause a time and concentration dependent proteolysis of rTFPI, resulting in the decrease of anti-factor Xa (measured by chromogenic substrate assay) and anticoagulant (measured by tissue factor-induced clotting assay) activities. Amino-terminal sequencing of the proteolytic fragments revealed that plasmin cleaved rTFPI at K86-T87, R107-G108, R199-A200, K249-G250, and K256-R257. Western blot analysis showed that proteolysis of exogenously added rTFPI also occurred in plasma supplemented with urokinase, and this is accompanied by decrease of anticoagulant activity. These changes were abolished by addition of aprotinin, an inhibitor of plasmin. These data indicate that TFPI is susceptible to proteolysis when plasma fibrinolytic system is activated. The results taken together suggest that plasmin degradation of TFPI may contribute to rethrombosis after thrombolysis, and may contribute to the variability of the efficacy of TFPI in various thrombolysis/reocclusion studies reported previously.
40
Cortesio, Christa L., Lindsy R. Boateng, Timothy M. Piazza, David A. Bennin, and Anna Huttenlocher. "Calpain-mediated Proteolysis of Paxillin Negatively Regulates Focal Adhesion Dynamics and Cell Migration." Journal of Biological Chemistry 286, no. 12 (January 26, 2011): 9998–10006. http://dx.doi.org/10.1074/jbc.m110.187294.
Full textAbstract:
The dynamic turnover of integrin-mediated adhesions is important for cell migration. Paxillin is an adaptor protein that localizes to focal adhesions and has been implicated in cell motility. We previously reported that calpain-mediated proteolysis of talin1 and focal adhesion kinase mediates adhesion disassembly in motile cells. To determine whether calpain-mediated paxillin proteolysis regulates focal adhesion dynamics and cell motility, we mapped the preferred calpain proteolytic site in paxillin. The cleavage site is between the paxillin LD1 and LD2 motifs and generates a C-terminal fragment that is similar in size to the alternative product paxillin delta. The calpain-generated proteolytic fragment, like paxillin delta, functions as a paxillin antagonist and impairs focal adhesion disassembly and migration. We generated mutant paxillin with a point mutation (S95G) that renders it partially resistant to calpain proteolysis. Paxillin-deficient cells that express paxillin S95G display increased turnover of zyxin-containing adhesions using time-lapse microscopy and also show increased migration. Moreover, cancer-associated somatic mutations in paxillin are common in the N-terminal region between the LD1 and LD2 motifs and confer partial calpain resistance. Taken together, these findings suggest a novel role for calpain-mediated proteolysis of paxillin as a negative regulator of focal adhesion dynamics and migration that may function to limit cancer cell invasion.
41
Mosoni, L., T. Malmezat, M. C. Valluy, M. L. Houlier, D. Attaix, and P. Patureau Mirand. "Lower recovery of muscle protein lost during starvation in old rats despite a stimulation of protein synthesis." American Journal of Physiology-Endocrinology and Metabolism 277, no. 4 (October 1, 1999): E608—E616. http://dx.doi.org/10.1152/ajpendo.1999.277.4.e608.
Full textAbstract:
Sarcopenia could result from the inability of an older individual to recover muscle lost during catabolic periods. To test this hypothesis, we compared the capacity of 5-day-refed 12- and 24-mo-old rats to recover muscle mass lost after 10 days without food. We measured gastrocnemius and liver protein synthesis with the flooding-dose method and also measured nitrogen balance, 3-methylhistidine excretion, and the gene expression of components of proteolytic pathways in muscle comparing fed, starved, and refed rats at each age. We show that 24-mo-old rats had an altered capacity to recover muscle proteins. Muscle protein synthesis, inhibited during starvation, returned to control values during refeeding in both age groups. The lower recovery in 24-mo-old rats was related to a lack of inhibition of muscle proteolysis during refeeding. The level of gene expression of components of the proteolytic pathways did not account for the variations in muscle proteolysis at both ages. In conclusion, this study highlights the role of muscle proteolysis in the lower recovery of muscle protein mass lost during catabolic periods.
42
Reboul, A., J. Arvieux, J. F. Wright, and M. G. Colomb. "Proteolytic fragmentation of tetanus toxin by subcellular fractions of JY, a B lymphoblastoid cell line." Biochemical Journal 277, no. 1 (July 1, 1991): 47–51. http://dx.doi.org/10.1042/bj2770047.
Full textAbstract:
Proteolysis of 125I-labelled tetanus toxin by subcellular fractions from an Epstein-Barr-virus-transformed B lymphoblastoid cell line, JY, was investigated. Fractions enriched in lysosomes and plasma membranes cleaved the toxin molecule at several sites, with a pH optimum of 5.5. N-Terminal sequence analysis of Mr-81,000, -45,000 and -35,000 proteolytic fragments indicated cleavage of the Asp-460-Leu-461, Asp-872-Glu-873 and Ile-1013-Thr-1014 peptide bonds, all sites located within the heavy chain of the toxin molecule. Additional sites near the C-terminus of the heavy chain, giving rise to low-Mr peptides, were implicated. The toxin light chain was more resistant to proteolysis. A similar pattern of fragmentation was observed with tetanus toxin biosynthetically radiolabelled with 14C-labelled amino acids, showing that the proteolysis was not an artifact caused by iodination. The proteolytic activity was inhibited by the serine proteinase inhibitor di-isopropyl phosphorofluoridate, thiol-blocking proteinase inhibitors N-ethylmaleimide and iodoacetamide, and by EDTA. These results represent a preliminary characterization of the processing in vitro of tetanus toxin by an antigen-presenting cell line.
43
Katrukha, Aleksei G., Anastasia V. Bereznikova, Vladimir L. Filatov, Tatiana V. Esakova, Olga V. Kolosova, Kim Pettersson, Timo Lövgren, et al. "Degradation of cardiac troponin I: implication for reliable immunodetection." Clinical Chemistry 44, no. 12 (December 1, 1998): 2433–40. http://dx.doi.org/10.1093/clinchem/44.12.2433.
Full textAbstract:
Abstract We have analyzed by different immunological methods the proteolytic degradation of cardiac troponin I (cTnI) in human necrotic tissue and in serum. cTnI is susceptible to proteolysis, and its degradation leads to the appearance of a wide diversity of proteolytic peptides with different stabilities. N- and C-terminal regions were rapidly cleaved by proteases, whereas the fragment located between residues 30 and 110 demonstrated substantially higher stability, possibly because of its protection by TnC. We conclude that antibodies selected for cTnI sandwich immunoassays should preferentially recognize epitopes located in the region resistant to proteolysis. Such an approach can be helpful for a much needed standardization of cTnI immunoassays and can improve the sensitivity and reproducibility of cTnI assays.
44
Mañas-García, Laura, Nuria Bargalló, Joaquim Gea, and Esther Barreiro. "Muscle Phenotype, Proteolysis, and Atrophy Signaling During Reloading in Mice: Effects of Curcumin on the Gastrocnemius." Nutrients 12, no. 2 (January 31, 2020): 388. http://dx.doi.org/10.3390/nu12020388.
Full textAbstract:
We hypothesized that curcumin may mitigate muscle protein degradation and loss through attenuation of proteolytic activity in limb muscles of mice exposed to reloading (7dR) following immobilization (7dI). In gastrocnemius of mice (female C57BL/6J, 10 weeks) exposed to recovery following a seven-day period of hindlimb immobilization with/without curcumin treatment, markers of muscle proteolysis (systemic troponin-I), atrophy signaling pathways and histone deacetylases, protein synthesis, and muscle phenotypic characteristics and function were analyzed. In gastrocnemius of reloading mice compared to unloaded, muscle function, structure, sirtuin-1, and protein synthesis improved, while proteolytic and signaling markers (FoxO1/3) declined. In gastrocnemius of unloaded and reloaded mice treated with curcumin, proteolytic and signaling markers (NF-kB p50) decreased and sirtuin-1 activity and hybrid fibers size increased (reloaded muscle), while no significant improvement was seen in muscle function. Treatment with curcumin elicited a rise in sirtuin-1 activity, while attenuating proteolysis in gastrocnemius of mice during reloading following a period of unloading. Curcumin attenuated muscle proteolysis probably via activation of histone deacetylase sirtuin-1, which also led to decreased levels of atrophy signaling pathways. These findings offer an avenue of research in the design of therapeutic strategies in clinical settings of patients exposed to periods of disuse muscle atrophy.
45
Mintoo, Mubashir, Amritangshu Chakravarty, and Ronak Tilvawala. "N-Terminomics Strategies for Protease Substrates Profiling." Molecules 26, no. 15 (August 3, 2021): 4699. http://dx.doi.org/10.3390/molecules26154699.
Full textAbstract:
Proteases play a central role in various biochemical pathways catalyzing and regulating key biological events. Proteases catalyze an irreversible post-translational modification called proteolysis by hydrolyzing peptide bonds in proteins. Given the destructive potential of proteolysis, protease activity is tightly regulated. Dysregulation of protease activity has been reported in numerous disease conditions, including cancers, neurodegenerative diseases, inflammatory conditions, cardiovascular diseases, and viral infections. The proteolytic profile of a cell, tissue, or organ is governed by protease activation, activity, and substrate specificity. Thus, identifying protease substrates and proteolytic events under physiological conditions can provide crucial information about how the change in protease regulation can alter the cellular proteolytic landscape. In recent years, mass spectrometry-based techniques called N-terminomics have become instrumental in identifying protease substrates from complex biological mixtures. N-terminomics employs the labeling and enrichment of native and neo-N-termini peptides, generated upon proteolysis followed by mass spectrometry analysis allowing protease substrate profiling directly from biological samples. In this review, we provide a brief overview of N-terminomics techniques, focusing on their strengths, weaknesses, limitations, and providing specific examples where they were successfully employed to identify protease substrates in vivo and under physiological conditions. In addition, we explore the current trends in the protease field and the potential for future developments.
46
Graef, Martin, Georgeta Seewald, and Thomas Langer. "Substrate Recognition by AAA+ ATPases: Distinct Substrate Binding Modes in ATP-Dependent Protease Yme1 of the Mitochondrial Intermembrane Space." Molecular and Cellular Biology 27, no. 7 (January 29, 2007): 2476–85. http://dx.doi.org/10.1128/mcb.01721-06.
Full textAbstract:
ABSTRACT The energy-dependent proteolysis of cellular proteins is mediated by conserved proteolytic AAA+ complexes. Two such machines, the m- and i-AAA proteases, are present in the mitochondrial inner membrane. They exert chaperone-like properties and specifically degrade nonnative membrane proteins. However, molecular mechanisms of substrate engagement by AAA proteases remained elusive. Here, we define initial steps of substrate recognition and identify two distinct substrate binding sites in the i-AAA protease subunit Yme1. Misfolded polypeptides are recognized by conserved helices in proteolytic and AAA domains. Structural modeling reveals a lattice-like arrangement of these helices at the surface of hexameric AAA protease ring complexes. While helices within the AAA domain apparently play a general role for substrate binding, the requirement for binding to surface-exposed helices within the proteolytic domain is determined by the folding and membrane association of substrates. Moreover, an assembly factor of cytochrome c oxidase, Cox20, serves as a substrate-specific cofactor during proteolysis and modulates the initial interaction of nonassembled Cox2 with the protease. Our findings therefore reveal the existence of alternative substrate recognition pathways within AAA proteases and shed new light on molecular mechanisms ensuring the specificity of proteolysis by energy-dependent proteases.
47
Voelkel-Johnson, C., A. J. Entingh, W. S. Wold, L. R. Gooding, and S. M. Laster. "Activation of intracellular proteases is an early event in TNF-induced apoptosis." Journal of Immunology 154, no. 4 (February 15, 1995): 1707–16. http://dx.doi.org/10.4049/jimmunol.154.4.1707.
Full textAbstract:
Abstract The serine protease inhibitor tosyl-argenine methyl ester inhibits TNF-induced apoptosis, suggesting that proteolysis is necessary for this response. To test this hypothesis, we asked whether protein fragmentation occurs during the death of C3HA fibroblasts, a 3T3-like cell that was rendered sensitive to TNF by cycloheximide. Our results show that the binding of fluorescamine, which binds primary amines, was increased in apoptotic cells by approximately 50%. We also found that 10-15% of the protein in apoptotic cells was no longer precipitable by TCA. Evidence for proteolysis was also revealed by SDS-PAGE analysis and from Western blots. We observed fragmentation and/or degradation of lamin B, topoisomerase I, histone H1, protein kinase C beta 1, and cPLA2, indicating that proteolysis during apoptosis is non-specific. We also found evidence of proteolysis in C3HA cells sensitized to TNF by the adenovirus dl758 (which lacks the E3 14.7-kDa resistance gene) suggesting that protease activation is common in TNF-induced apoptosis. In contrast, the adenovirus E3 14.7-kDa resistance gene prevented proteolysis suggesting that this protein acts at, or upstream of the proteases activated in this response. Finally, because tosyl-argenine methyl ester inhibits the release of [3H]arachidonic acid from apoptotic cells, we tested whether proteolysis of cPLA2 is necessary for enzyme activation. Our results failed, however, to reveal a common proteolytic fragment in different cell types, and when tested in vitro the cytosol from apoptotic cells had less cPLA2 activity. It is unlikely, therefore, that proteolysis is necessary for the activation of this enzyme during TNF-induced apoptosis.
48
Chang, Hao, Philip M. Smallwood, John Williams, and Jeremy Nathans. "Intramembrane Proteolysis of Astrotactins." Journal of Biological Chemistry 292, no. 8 (January 18, 2017): 3506–16. http://dx.doi.org/10.1074/jbc.m116.768077.
Full textAbstract:
Astrotactins are vertebrate-specific membrane proteins implicated in neuron-glia interactions during central nervous system development and in hair follicle polarity during skin development. By studying epitope-tagged derivatives of mouse astrotactin-2 (Astn2) produced in transfected cells, we determined that the amino and carboxyl termini reside in the extracellular space and are initially linked by two transmembrane segments and a single cytoplasmic domain. We further show that Astn2 undergoes proteolytic cleavage in the second transmembrane domain (TM2) and that a disulfide bond holds the resulting two fragments together. Recombinant Astn1 also undergoes TM2 cleavage, as does Astn2 isolated from mouse cerebellum. Astn2 intramembrane proteolysis is insensitive to replacement of TM2 by the transmembrane domain of CD74 or by 21 alanines. However, replacement of TM2 by the transmembrane domain of CD4, the asialoglycoprotein receptor, or the transferrin receptor eliminates intramembrane proteolysis, as does leucine substitution of residues that overlap or are immediately upstream of the cleavage site. Replacement of the transmembrane domain of CD74 or the asialoglycoprotein receptor with Astn2 TM2 leads to the appearance of a carboxyl-terminal fragment consistent with intramembrane proteolysis. These experiments define a highly unusual transmembrane topology for the astrotactins, reveal intramembrane proteolysis as a feature of astrotactin maturation, and constrain the substrate sequences that are permissive for cleavage of one type 2 transmembrane segment.
49
Ward, Donald E., Keith R. Shockley, Lara S. Chang, Ryan D. Levy, Joshua K. Michel, Shannon B. Conners, and Robert M. Kelly. "Proteolysis in hyperthermophilic microorganisms." Archaea 1, no. 1 (2002): 63–74. http://dx.doi.org/10.1155/2002/503191.
Full textAbstract:
Proteases are found in every cell, where they recognize and break down unneeded or abnormal polypeptides or peptide-based nutrients within or outside the cell. Genome sequence data can be used to compare proteolytic enzyme inventories of different organisms as they relate to physiological needs for protein modification and hydrolysis. In this review, we exploit genome sequence data to compare hyperthermophilic microorganisms from the euryarchaeotal genusPyrococcus, the crenarchaeoteSulfolobus solfataricus, and the bacteriumThermotoga maritima. An overview of the proteases in these organisms is given based on those proteases that have been characterized and on putative proteases that have been identified from genomic sequences, but have yet to be characterized. The analysis revealed both similarities and differences in the mechanisms utilized for proteolysis by each of these hyperthermophiles and indicated how these mechanisms relate to proteolysis in less thermophilic cells and organisms.
50
Debigaré, Richard, and S. Russ Price. "Proteolysis, the ubiquitin-proteasome system, and renal diseases." American Journal of Physiology-Renal Physiology 285, no. 1 (July 2003): F1—F8. http://dx.doi.org/10.1152/ajprenal.00244.2002.
Full textAbstract:
Protein degradation is a critical process for the growth and function of cells. Proteolysis eliminates abnormal proteins, controls many cellular regulatory processes, and supplies amino acids for cellular remodeling. When substrates of proteolytic pathways are poorly recognized or there is mistiming of proteolysis, profound changes in cell function can occur. Based on these potential problems, it is not surprising that alterations in proteolytic enzymes/cofactors or in the structure of protein substrates that render them more or less susceptible to degradation are responsible for disorders associated with kidney cell malfunctions. Multiple pathways exist for protein degradation. The best-described proteolytic system is the ubiquitin-proteasome pathway, which requires ATP and degrades the bulk of cellular and some membrane proteins. This review will survey examples of renal abnormalities that are associated with defective protein degradation involving the ubiquitin-proteasome pathway. Loss of muscle mass associated with chronic renal failure, von Hippel-Lindau disease, Liddle syndrome, and ischemic acute renal failure will be discussed. These examples are indicative of the diverse roles of the ubiquitin-proteasome system in renal-associated pathological conditions.