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Journal articles on the topic 'Metabolism; Cytosol'

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Published: 4 June 2021
Last updated: 3 February 2022

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1

Mikšanová, Markéta, Petr Novák, Eva Frei, and Marie Stiborová. "Metabolism of Carcinogenic 2-Nitroanisole in Rat, Rabbit, Porcine and Human Hepatic Cytosol." Collection of Czechoslovak Chemical Communications 69, no. 3 (2004): 589–602. http://dx.doi.org/10.1135/cccc20040589.

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We investigated the ability of hepatic cytosolic samples from human, rat, rabbit and pig to metabolize an important industrial pollutant and a potent carcinogen for rodents, 2-nitroanisole (1-methoxy-2-nitrobenzene). A comparison between experimental animals and the human enzymatic system is essential for the extrapolation of animal carcinogenicity data to humans to assess a health risk to humans. Two major metabolites produced from 2-nitroanisole by cytosols of all species were N-(2-methoxyphenyl)hydroxylamine and 2-methoxyaniline. An additional minor product of 2-nitroanisole metabolism has not yet been characterized. Both the identified metabolites are generated from 2-nitroanisole by reduction of the nitro group. To define the role of cytosolic reductases in the reduction of 2-nitroanisole, we investigated the modulation of 2-nitroanisole reduction by cofactors of the cytosolic reductases, DT-diaphorase and xanthine oxidase. The role of the human enzymes in 2-nitroanisole reduction was also investigated by correlating the xanthine oxidase-linked catalytic activities in each human cytosolic sample with the concentration of the 2-nitroanisole reduction product, 2-methoxyaniline, formed by the action of the same cytosol. On the basis of these analyses, most of hepatic cytosolic reduction of 2-nitroanisole was attributed to xanthine oxidase, but participation of DT-diaphorase in the reduction of this carcinogen in hepatic cytosols of rabbit and pigs cannot be excluded. Using the purified xanthine oxidase, its participation in 2-nitroanisole reduction was confirmed. The data clearly demonstrate the predominant role of xanthine oxidase in 2-nitroanisole reduction in human and rat hepatic cytosols and suggest a carcinogenic potency of this rodent carcinogen for humans.
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2

Cruz, Rogério Santos de Oliveira, Rafael Alves de Aguiar, Tiago Turnes, Rafael Penteado Dos Santos, Mariana Fernandes Mendes de Oliveira, and Fabrizio Caputo. "Intracellular Shuttle: The Lactate Aerobic Metabolism." Scientific World Journal 2012 (2012): 1–8. http://dx.doi.org/10.1100/2012/420984.

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Lactate is a highly dynamic metabolite that can be used as a fuel by several cells of the human body, particularly during physical exercise. Traditionally, it has been believed that the first step of lactate oxidation occurs in cytosol; however, this idea was recently challenged. A new hypothesis has been presented based on the fact that lactate-to-pyruvate conversion cannot occur in cytosol, because the LDH enzyme characteristics and cytosolic environment do not allow the reaction in this way. Instead, the Intracellular Lactate Shuttle hypothesis states that lactate first enters in mitochondria and only then is metabolized. In several tissues of the human body this idea is well accepted but is quite resistant in skeletal muscle. In this paper, we will present not only the studies which are protagonists in this discussion, but the potential mechanism by which this oxidation occurs and also a link between lactate and mitochondrial proliferation. This new perspective brings some implications and comes to change our understanding of the interaction between the energy systems, because the product of one serves as a substrate for the other.
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Greger, Janusz, and Fabianowska-Majewska Krystyna. "Different Effect Of Dgtp On 2'-Deoxyadenosine Metabolism In Mitochondria And Cytosol." Zeitschrift für Naturforschung C 47, no. 11-12 (December 1, 1992): 893–97. http://dx.doi.org/10.1515/znc-1992-11-1217.

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Two enzymes participating in 2′-deoxyadenosine (dAdo) metabolism: dAdo kinase (dAdoK EC 2.7.1.76) and adenosine deaminase (ADA, EC 3.5.4.4) were partially purified from rat liver mitochondria and cytosol and influence of nucleosides and nucleotides on the activity of these enzymes were investigated. Mitochondrial and cytosol dAdoK are separate proteins, while ADA from both subcellular fractions possesses similar physical properties. dGTP, a com petitive inhibitor of mitochondrial dAdoK, inhibits cytosol ADA in a mixed way but activates mitochondrial ADA and cytosol dAdoK. A possible effect of dGTP on dAdo metabolism in mitochondria and cytosol is discussed
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4

Herington, A. C., J. Stevenson, L. Coulson, and S. Ymer. "Characterization of a soluble prolactin-binding activity in rat liver cytosol." Journal of Endocrinology 109, no. 1 (April 1986): 61–66. http://dx.doi.org/10.1677/joe.0.1090061.

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ABSTRACT Soluble binding activity for lactogenic hormones has been detected in high-speed cytosolic preparations from the livers of 21-day-old male and female rats. No lactogenic hormone binding was detected in cytosols from rat heart, kidney, skeletal muscle or adipose tissue. Liver cytosol binding of 125I-labelled human growth hormone or ovine prolactin was dependent on time, temperature, and protein and calcium concentrations. Binding was specific for lactogenic hormones and not somatotrophic hormones. Scatchard analysis revealed linear plots with an affinity of 2·9–4·6 litres/ nmol. By gel filtration the molecular weight of the lactogen-binding activity was > 450 000. The cytosolic binding activity may be an internalized form of the membrane-bound lactogen receptor, which has similar binding characteristics, or alternatively it may be a distinct binding species, with a defined role in mediating intracellular effects of prolactin in the liver. J. Endocr. (1986) 109, 61–66
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5

Zhou, Lufang, Jennifer E. Salem, Gerald M. Saidel, William C. Stanley, and Marco E. Cabrera. "Mechanistic model of cardiac energy metabolism predicts localization of glycolysis to cytosolic subdomain during ischemia." American Journal of Physiology-Heart and Circulatory Physiology 288, no. 5 (May 2005): H2400—H2411. http://dx.doi.org/10.1152/ajpheart.01030.2004.

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A new multidomain mathematical model of cardiac cellular metabolism was developed to simulate metabolic responses to reduced myocardial blood flow. The model is based on mass balances and reaction kinetics that describe transport and metabolic processes of 31 key chemical species in cardiac tissue. The model has three distinct domains (blood, cytosol, and mitochondria) with interdomain transport of chemical species. In addition to distinguishing between cytosol and mitochondria, the model includes a subdomain in the cytosol to account for glycolytic metabolic channeling. Myocardial ischemia was induced by a 60% reduction in coronary blood flow, and model simulations were compared with experimental data from anesthetized pigs. Simulations with a previous model without compartmentation showed a slow activation of glycogen breakdown and delayed lactate production compared with experimental results. The addition of a subdomain for glycolysis resulted in simulations showing faster rates of glycogen breakdown and lactate production that closely matched in vivo experimental data. The dynamics of redox (NADH/NAD+) and phosphorylation (ADP/ATP) states were also simulated. These controllers are coupled to energy transfer reactions and play key regulatory roles in the cytosol and mitochondria. Simulations showed a similar dynamic response of the mitochondrial redox state and the rate of pyruvate oxidation during ischemia. In contrast, the cytosolic redox state displayed a time response similar to that of lactate production. In conclusion, this novel mechanistic model effectively predicted the rapid activation of glycogen breakdown and lactate production at the onset of ischemia and supports the concept of localization of glycolysis to a subdomain of the cytosol.
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6

Barlow, John W., Andrea J. Curtis, Lorna E. Raggatt, Nicole M. Loidl, Duncan J. Topliss, and Jan R. Stockigt. "Drug competition for intracellular triiodothyronine-binding sites." European Journal of Endocrinology 130, no. 4 (April 1994): 417–21. http://dx.doi.org/10.1530/eje.0.1300417.

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Barlow JW, Curtis AJ, Raggatt LE, Loidl NM, Topliss DJ. Stockigt JR. Drug competition for intracellular triiodothyronine-binding sites. Eur J Endocrinol 1944;130:417–21. ISSN 0804–4643 A variety of substances, including frusemide, non-esterified fatty acids (NEFAs) and non-steroidal antiinflammatory drugs (NSAIDs), can compete for triiodothyronine (T3)-binding sites in serum and at the cell surface. We examined the competitive potency of these agents at intracellular T3-binding sites in order to assess their potential to act as T3 antagonists. Competition for [125I]T3 binding was determined using hydroxyapatite separation in cytosols and nuclear extracts prepared from livers of Macaca fascicularis. The T3 affinities were 15.8 ± 1.2 nmol/l in cytosol and 0.23 ± 0.02 nmol/l in nuclear extract. Does–response curves were analysed by a four-parameter sigmoid curve-fitting program to determine competitor potency. The nineteen agents tested included various NSAIDs, NEFAs, non-bile acid cholephils (NBACs), frusemide, amiodarone and the flavonoid EMD 21388. In nuclear extract the most active competitors were linoleic acid (8.5 μmol/l) and linolenic acid (7.8 μmol/l), Potencies of NSAIDs varied between 66 μmol/l (meclofenamic acid) and 525 μmol/l (diclofenac). In cytosol, NEFAs were less potent but NSAIDs were stronger competitors than in nuclear extract. Half-inhibitory potencies in cytosol were between 13.2 μmol/l (meclofenamic acid) and 63.1 μmol/l (flufenamic acid). The NBAC bromosulphthalein was one of the most potent inhibitors in both cytosol and nuclear extract. When expressed relative to T3, diclofenac was a more effective competitor in cytosol than it was in nuclear extract. Amiodarone and EMD 21388 were without effect both in cytosol and nuclear extract. Frusemide (759 μmol/l) was weakly active in cytosol only. The action of T3 was assessed by measuring secretion of sex hormone-binding globulin (SHBG) in Hep-G2 cells. After 3 days with total T3 (0.1 μmol/l), SHBG was 155 ± 15% of the control. Amiodarone (100 μmol/l) and meclofenamic acid (100 μmol/l) were cytotoxic. Bromosulphthalein (10 μmol/l), one of the most potent competitors at both the cytoplasmic and the nuclear level, did not influence the T3-induced rise in SHBG secretion. None of the drugs tested affected the magnitude of maximal induction of SHBG by T3. Substances that compete for serum and cell surface T3-binding sites are also weak competitors for intracellular T3-binding proteins, although the heirarchy of potency differs. Frusemide and diclofenac, with a greater relative potency for cytosolic binding than nuclear binding, may have potential use in investigating the function of cytosolic T3-binding. Amiodarone shows no binding activity and is not a hormone antagonist in primate hepatic tissue. John W Barlow, Ewen Downie Metabolic Unit, Alfred Hospital, Commercial Road, Melbourne, Victoria 3181, Australia
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7

McMorris, Trevor C., Anissa N. Elayadi, Jian Yu, and Michael J. Kelner. "Metabolism of antitumor acylfulvene by rat liver cytosol." Biochemical Pharmacology 57, no. 1 (January 1999): 83–88. http://dx.doi.org/10.1016/s0006-2952(98)00273-1.

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8

Evans, M. A., R. Bhat, C. Papazafiratou, and D. Vidyasagar. "Effect of Hepatic Cytosol on Postnatal Drug Metabolism." Developmental Pharmacology and Therapeutics 10, no. 3 (1987): 199–211. http://dx.doi.org/10.1159/000457745.

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9

Penning, Trevor M. "Indomethacin and glucocorticoid metabolism in rat liver cytosol." Biochemical Pharmacology 35, no. 23 (December 1986): 4203–9. http://dx.doi.org/10.1016/0006-2952(86)90696-9.

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10

Myers, Steven R., Jerry W. Blake, and James W. Flesher. "Metabolism of 3-methylcholanthrene in rat liver cytosol." Chemico-Biological Interactions 71, no. 4 (1989): 393–401. http://dx.doi.org/10.1016/0009-2797(89)90113-0.

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11

Nakamura, Hirotoshi, Toshihiko Yokota, Hiroo Imura, and Leslie J. DeGroot. "Early effect of thyroid hormone on cytosolic protein phosphorylation in rat anterior pituitary." Acta Endocrinologica 109, no. 3 (July 1985): 326–29. http://dx.doi.org/10.1530/acta.0.1090326.

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Abstract. The effect of T3 was studied on phosphorylation of cytosolic proteins in rat anterior pituitary. Cytosols obtained from hypothyroid (H) and T3 (50 μg/100 g body weight) injected H rats (T) were phosphorylated in vitro. Although total incorporation of 32P into proteins did not differ between H and T, analysis of phosphoproteins by SDS polyacrylamide gel electrophoresis and autoradiography revealed that T3 injection significantly increased phosphorylation of 2 proteins within 1 h. These results and our previous demonstration of T3 effects on phosphorylation in rat liver cytosol and cultured human skin fibroblasts suggest that protein phosphorylation is an important early intracellular process in T3 action.
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12

Saheki, Takeyori, Mitsuaki Moriyama, Aki Funahashi, and Eishi Kuroda. "AGC2 (Citrin) Deficiency—From Recognition of the Disease till Construction of Therapeutic Procedures." Biomolecules 10, no. 8 (July 24, 2020): 1100. http://dx.doi.org/10.3390/biom10081100.

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Can you imagine a disease in which intake of an excess amount of sugars or carbohydrates causes hyperammonemia? It is hard to imagine the intake causing hyperammonemia. AGC2 or citrin deficiency shows their symptoms following sugar/carbohydrates intake excess and this disease is now known as a pan-ethnic disease. AGC2 (aspartate glutamate carrier 2) or citrin is a mitochondrial transporter which transports aspartate (Asp) from mitochondria to cytosol in exchange with glutamate (Glu) and H+. Asp is originally supplied from mitochondria to cytosol where it is necessary for synthesis of proteins, nucleotides, and urea. In cytosol, Asp can be synthesized from oxaloacetate and Glu by cytosolic Asp aminotransferase, but oxaloacetate formation is limited by the amount of NAD+. This means an increase in NADH causes suppression of Asp formation in the cytosol. Metabolism of carbohydrates and other substances which produce cytosolic NADH such as alcohol and glycerol suppress oxaloacetate formation. It is forced under citrin deficiency since citrin is a member of malate/Asp shuttle. In this review, we will describe history of identification of the SLC25A13 gene as the causative gene for adult-onset type II citrullinemia (CTLN2), a type of citrin deficiency, pathophysiology of citrin deficiency together with animal models and possible treatments for citrin deficiency newly developing.
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13

Snell, K., and D. A. Duff. "Branched-chain amino acid metabolism and alanine formation in rat muscles in vitro. Mitochondrial-cytosolic interrelationships." Biochemical Journal 225, no. 3 (February 1, 1985): 737–43. http://dx.doi.org/10.1042/bj2250737.

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Muscle branched-chain amino acid metabolism is coupled to alanine formation via branched-chain amino acid aminotransferase and alanine aminotransferase, but the subcellular distributions of these and other associated enzymes are uncertain. Recovery of branched-chain aminotransferase in the cytosol fraction after differential centrifugation was shown to be accompanied by leakage of mitochondrial-matrix marker enzymes. By using a differential fractional extraction procedure, most of the branched-chain aminotransferase activity in rat muscle was located in the mitochondrial compartment, whereas alanine aminotransferase was predominantly in the cytosolic compartment. Phosphoenolpyruvate carboxykinase, like aspartate aminotransferase, was approximately equally distributed between these subcellular compartments. This arrangement necessitates a transfer of branched-chain amino nitrogen and carbon from the mitochondria to the cytosol for alanine synthesis de novo to occur. In incubations of hemidiaphragms from 48 h-starved rats with 3mM-valine or 3mM-glutamate, the stimulation of alanine release was inhibited by 69% by 1 mM-aminomethoxybut-3-enoate, a selective inhibitor of aspartate aminotransferase. Leucine-stimulated alanine release was unaffected. These data implicate aspartate aminotransferase in the transfer of amino acid carbon and nitrogen from the mitochondria to the cytosol, and suggest that oxaloacetate, via phosphoenolpyruvate carboxykinase, can serve as an intermediate on the route of pyruvate formation for muscle alanine synthesis.
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14

Leskovac, Vladimir, and Anthony D. Theoharides. "Hepatic metabolism of artemisinin drugs—II. Metabolism of arteether in rat liver cytosol." Comparative Biochemistry and Physiology Part C: Comparative Pharmacology 99, no. 3 (January 1991): 391–96. http://dx.doi.org/10.1016/0742-8413(91)90262-r.

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15

Zhang, Bo, Ross Carlson, and Friedrich Srienc. "Engineering the Monomer Composition of Polyhydroxyalkanoates Synthesized in Saccharomyces cerevisiae." Applied and Environmental Microbiology 72, no. 1 (January 2006): 536–43. http://dx.doi.org/10.1128/aem.72.1.536-543.2006.

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ABSTRACT Polyhydroxyalkanoates (PHAs) have received considerable interest as renewable-resource-based, biodegradable, and biocompatible plastics with a wide range of potential applications. We have engineered the synthesis of PHA polymers composed of monomers ranging from 4 to 14 carbon atoms in either the cytosol or the peroxisome of Saccharomyces cerevisiae by harnessing intermediates of fatty acid metabolism. Cytosolic PHA production was supported by establishing in the cytosol critical β-oxidation chemistries which are found natively in peroxisomes. This platform was utilized to supply medium-chain (C6 to C14) PHA precursors from both fatty acid degradation and synthesis to a cytosolically expressed medium-chain-length (mcl) polymerase from Pseudomonas oleovorans. Synthesis of short-chain-length PHAs (scl-PHAs) was established in the peroxisome of a wild-type yeast strain by targeting the Ralstonia eutropha scl polymerase to the peroxisome. This strain, harboring a peroxisomally targeted scl-PHA synthase, accumulated PHA up to approximately 7% of its cell dry weight. These results indicate (i) that S. cerevisiae expressing a cytosolic mcl-PHA polymerase or a peroxisomal scl-PHA synthase can use the 3-hydroxyacyl coenzyme A intermediates from fatty acid metabolism to synthesize PHAs and (ii) that fatty acid degradation is also possible in the cytosol as β-oxidation might not be confined only to the peroxisomes. Polymers of even-numbered, odd-numbered, or a combination of even- and odd-numbered monomers can be controlled by feeding the appropriate substrates. This ability should permit the rational design and synthesis of polymers with desired material properties.
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Pou, S., W. S. Pou, G. M. Rosen, and E. E. el-Fakahany. "N-hydroxylamine is not an intermediate in the conversion of l-arginine to an activator of soluble guanylate cyclase in neuroblastoma N1E-115 cells." Biochemical Journal 273, no. 3 (February 1, 1991): 547–52. http://dx.doi.org/10.1042/bj2730547.

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This study evaluates the role of N-hydroxylamine (NH2OH) in activating soluble guanylate cyclase in the mouse neuroblastoma clone N1E-115. It has been proposed that NH2OH is a putative intermediate in the biochemical pathway for the generation of nitric oxide (NO)/endothelium-derived relaxing factor (EDRF) from L-arginine. NH2OH caused a time- and concentration-dependent increase in cyclic GMP formation in intact cells. This response was not dependent on Ca2+. In cytosol preparations the activation of guanylate cyclase by L-arginine was dose-dependent and required Ca2+ and NADPH. In contrast, NH2OH itself did not activate cytosolic guanylate cyclase but it inhibited the basal activity of this enzyme in a concentration-dependent manner. The formation of cyclic GMP in the cytosolic fractions in response to NH2OH required the addition of catalase and H2O2. On the other hand, catalase and/or H2O2 lead to a decrease in L-arginine-induced cyclic GMP formation. Furthermore, NH2OH inhibited L-arginine- and sodium nitroprusside-induced cyclic GMP formation in the cytosol. The inhibition of L-arginine-induced cyclic GMP formation in the cytosol by NH2OH was not reversed by the addition of superoxide dismutase. These data strongly suggest that NH2OH is not a putative intermediate in the metabolism of L-arginine to an activator of guanylate cyclase.
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17

Mehra, R. K., and I. Bremner. "Studies on the metabolism of rat liver copper-metallothionein." Biochemical Journal 227, no. 3 (May 1, 1985): 903–8. http://dx.doi.org/10.1042/bj2270903.

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The degradation of purified 35S-labelled rat liver isometallothioneins (MT) by lysosomal extracts was studied. Zn-MT-I was more readily hydrolysed than Zn-MT-II, but no significant degradation of the Cu-containing metallothioneins could be detected, even after 24 h incubation. The susceptibility of MT to degradation in vitro may be related to the strength of the metal-thiolate bonds. However, the turnover rates of cytosolic MT in vivo, as established by pulse-labelling techniques, are apparently subject to different controls. The half-lives of MT-I and -II in the liver cytosol of Cu2+-injected rats were only 15.4 +/- 1.5 and 18.2 +/- 1.1 h respectively. Approx. 25% of the total liver MT was present in particulate fractions (probably in lysosomes) of the liver and had a half-life of 25.1 +/- 4.1 h.
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18

Judge, Ayesha, and Michael S. Dodd. "Metabolism." Essays in Biochemistry 64, no. 4 (August 24, 2020): 607–47. http://dx.doi.org/10.1042/ebc20190041.

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Abstract Metabolism consists of a series of reactions that occur within cells of living organisms to sustain life. The process of metabolism involves many interconnected cellular pathways to ultimately provide cells with the energy required to carry out their function. The importance and the evolutionary advantage of these pathways can be seen as many remain unchanged by animals, plants, fungi, and bacteria. In eukaryotes, the metabolic pathways occur within the cytosol and mitochondria of cells with the utilisation of glucose or fatty acids providing the majority of cellular energy in animals. Metabolism is organised into distinct metabolic pathways to either maximise the capture of energy or minimise its use. Metabolism can be split into a series of chemical reactions that comprise both the synthesis and degradation of complex macromolecules known as anabolism or catabolism, respectively. The basic principles of energy consumption and production are discussed, alongside the biochemical pathways that make up fundamental metabolic processes for life.
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19

Esterbauer, H., H. Zollner, and J. Lang. "Metabolism of the lipid peroxidation product 4-hydroxynonenal by isolated hepatocytes and by liver cytosolic fractions." Biochemical Journal 228, no. 2 (June 1, 1985): 363–73. http://dx.doi.org/10.1042/bj2280363.

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The metabolism of the lipid peroxidation product 4-hydroxynonenal and of several other related aldehydes by isolated hepatocytes and rat liver subcellular fractions has been investigated. Hepatocytes rapidly metabolize 4-hydroxynonenal in an oxygen-independent process with a maximum rate (depending on cell preparation) ranging from 130 to 230 nmol/min per 10(6) cells (average 193 +/- 50). The aldehyde is also rapidly utilized by whole rat liver homogenate and the cytosolic fraction (140 000 g supernatant) supplemented with NADH, whereas purified nuclei, mitochondria and microsomes supplemented with NADH show no noteworthy consumption of the aldehyde. In cytosol, the NADH-mediated metabolism of the aldehyde exhibits a 1:1 stoichiometry, i.e. 1 mol of NADH oxidized/mol of hydroxynonenal consumed, and the apparent Km value for the aldehyde is 0.1 mM. Addition of pyrazole (10 mM) or heat inactivation of the cytosol completely abolishes aldehyde metabolism. The various findings strongly suggest that hepatocytes and rat liver cytosol respectively convert 4-hydroxynonenal enzymically is the corresponding alcohol, non-2-ene-1,4-diol, according to the equation: CH3-[CH2]4-CH(OH)-CH = CH-CHO + NADH + H+→CH3-[CH2]4-CH(OH)-CH = CH-CH2OH + NAD+. The alcohol non-2-ene-1,4-diol has not yet been isolated from incubations with hepatocytes and liver cytosolic fractions, but was isolated in pure form from an incubation mixture containing 4-hydroxynonenal, isolated liver alcohol dehydrogenase and NADH and its chemical structure was confirmed by mass spectroscopy. Compared with liver, all other tissues possess only little ability to metabolize 4-hydroxynonenal, ranging from 0% (fat pads) to a maximal 10% (kidney) of the activity present in liver. The structure of the aldehyde has a strong influence on the rate and extent of its enzymic NADH-dependent reduction to the alcohol. The saturated analogue nonanal is a poor substrate and only a small proportion of it is converted to the alcohol. Similarly, nonenal is much less readily utilized as compared with 4-hydroxynonenal. The effective conversion of the cytotoxic 4-hydroxynonenal and other reactive aldehydes to alcohols, which are probably less toxic, could play a role in the general defence system of the liver against toxic products arising from radical-induced lipid peroxidation.
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20

ROWLAND, K., L. LENNARD, and J. S. LILLEYMAN. "In vitro metabolism of 6-mercaptopurine by human liver cytosol." Xenobiotica 29, no. 6 (January 1999): 615–28. http://dx.doi.org/10.1080/004982599238434.

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Ishizuka, Aya, Yuki Hashimto, Ryosuke Naka, Mitsuhiro Kinoshita, Kazuaki Kakehi, Junichi Seino, Yoko Funakoshi, Tadashi Suzuki, Akihiko Kameyama, and Hisashi Narimatsu. "Accumulation of free complex-type N-glycans in MKN7 and MKN45 stomach cancer cells." Biochemical Journal 413, no. 2 (June 26, 2008): 227–37. http://dx.doi.org/10.1042/bj20071562.

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During the N-glycosylation reaction, it has been shown that ‘free’ N-glycans are generated either from lipid-linked oligosaccharides or from misfolded glycoproteins. In both cases, occurrence of high mannose-type free glycans is well-documented, and the molecular mechanism for their catabolism in the cytosol has been studied. On the other hand, little, if anything, is known with regard to the accumulation of more processed, complex-type free oligosaccharides in the cytosol of mammalian cells. During the course of comprehensive analysis of N-glycans in cancer cell membrane fractions [Naka et al. (2006) J. Proteome Res. 5, 88–97], we found that a significant amount of unusual, complex-type free N-glycans were accumulated in the stomach cancer-derived cell lines, MKN7 and MKN45. The most abundant and characteristic glycan found in these cells was determined to be NeuAcα2-6Galβ1-4GlcNAcβ1-2Manα1-3Manβ1-4GlcNAc. Biochemical analyses indicated that those glycans found were cytosolic glycans derived from lysosomes due to low integrity of the lysosomal membrane. Since the accumulation of these free N-glycans was specific to only two cell lines among the various cancer cell lines examined, these cytosolic N-glycans may serve as a specific biomarker for diagnosis of specific tumours. A cytosolic sialidase, Neu2, was shown to be involved in the degradation of these sialoglycans, indicating that the cytosol of mammalian cells might be equipped for metabolism of complex-type glycans.
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Nemoto, Shino, Kazuyo Takeda, Zu-Xi Yu, Victor J. Ferrans, and Toren Finkel. "Role for Mitochondrial Oxidants as Regulators of Cellular Metabolism." Molecular and Cellular Biology 20, no. 19 (October 1, 2000): 7311–18. http://dx.doi.org/10.1128/mcb.20.19.7311-7318.2000.

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ABSTRACT Leakage of mitochondrial oxidants contributes to a variety of harmful conditions ranging from neurodegenerative diseases to cellular senescence. We describe here, however, a physiological and heretofore unrecognized role for mitochondrial oxidant release. Mitochondrial metabolism of pyruvate is demonstrated to activate the c-Jun N-terminal kinase (JNK). This metabolite-induced rise in cytosolic JNK1 activity is shown to be triggered by increased release of mitochondrial H2O2. We further demonstrate that in turn, the redox-dependent activation of JNK1 feeds back and inhibits the activity of the metabolic enzymes glycogen synthase kinase 3β and glycogen synthase. As such, these results demonstrate a novel metabolic regulatory pathway activated by mitochondrial oxidants. In addition, they suggest that although chronic oxidant production may have deleterious effects, mitochondrial oxidants can also function acutely as signaling molecules to provide communication between the mitochondria and the cytosol.
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FUJIKAWA, Y., N. SAKURAI, S. SENDO, T. OKA, H. YAMANA, K. G. OFOSU-BUDU, H. EL-SHEMY, and K. FUJITA. "Sugar metabolism in expanding husk leaves of flint corn (Zea mays L.) genotypes differing in husk leaf size." Journal of Agricultural Science 139, no. 1 (August 2002): 37–45. http://dx.doi.org/10.1017/s0021859602002319.

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Relationships between leaf expansion and MeOH-soluble (cytosol) and cell-wall fractions, and their sugar composition prior to silking in flint corn lines were studied. A greater husk leaf area of one genotype, X-15 is mainly due to prolonged and higher rate of expansion. Prior to rapid expansion of husk leaf area, neutral sugars in the cytosol fraction accounted for most of the non-starch carbohydrates (56–62%), while hemicellulose and cellulose fractions accounted for less than 20%. In mature leaf parts, however, sugars in the cytosol fraction decreased but those in hemicellulose and cellulose fractions increased by 30% and 42%, respectively. The predominant sugar in the cytosol fraction was glucose (Glc), while in the hemicellulose fraction xylose (Xyl) and arabinose (Ara) dominated. During rapid expansion of husk leaves, 13C was incorporated at a higher rate into hemicellulose than cellulose, and this process was more active in X-15 than in other genotypes. During an identical period, 13C atom % excess in Xyl increased markedly in the hemicellulose fraction, however it remained low in the cytosol one. The current results suggest that synthesis of Xyl and xylan plays an important role in renewal of hemicellulose, which may be required for expansion.
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24

Richardson, DR, P. Ponka, and D. Vyoral. "Distribution of iron in reticulocytes after inhibition of heme synthesis with succinylacetone: examination of the intermediates involved in iron metabolism." Blood 87, no. 8 (April 15, 1996): 3477–88. http://dx.doi.org/10.1182/blood.v87.8.3477.bloodjournal8783477.

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Succinylacetone (SA) is an inhibitor of heme synthesis that acts on the enzyme delta-aminolevulinic acid dehydratase. When reticulocytes are incubated with 59Fe-transferrin (59Fe-Tf) in the presence of SA, there is an accumulation of 59Fe in the mitochondrion and in a cytosolic non- heme intermediate that has been described as a putative Fe transporter (Adams et al, Biochim Biophys Acta 1012:243, 1989). Considering these observations, the present study was designed to examine the intermediates of Fe metabolism in control and SA-treated reticulocytes. This investigation showed that in the cytosol of control cells, most 59Fe was incorporated into hemoglobin (Hb) with a minor amount entering ferritin. In addition, a previously unrecognized cytosolic intermediate was identified (band X) that was absent when heme synthesis was inhibited with SA. Upon reincubation of SA-treated reticulocytes with protoporphyrin IX, band X initially increased in intensity and then decreased later in the incubation. In contrast, when 59Fe-labeled control cells were reincubated in the presence of SA and unlabeled diferric Tf, there was a marked decrease in the intensity of band X. These experiments suggest that component X may be an intermediate involved in the transfer of heme in the cytosol. Alternatively, these data could also be interpreted as indicating that band X may be a short- lived hemoprotein. We have confirmed the presence of an 59Fe-containing molecule in the cytosol of SA-treated reticulocytes (band Y) that is not present in control cells. However, when cells were incubated with 59Fe-Tf plus SA and then chased in the presence of SA and unlabeled diferric Tf, there was no decrease in this cytosolic pool of Fe, suggesting that it was not a intermediate supplying Fe for either ferritin or heme synthesis. Finally, there is little low molecular weight (Mr) Fe in reticulocytes, and our studies suggest that the low- Mr Fe present does not behave as an intermediate. Moreover, after inhibition of heme synthesis with SA, 59Fe in the low-Mr compartment was markedly decreased, suggesting that this component may be heme or a low-Mr heme-containing molecule. Considering the apparent lack of a cytosolic Fe transporter in rabbit reticulocytes, an alternative model of intracellular Fe transport is proposed that does not implicate a potentially toxic intermediate pool of low-Mr Fe complexes.
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25

Bramley, T. A., G. S. Menzies, A. S. McNeilly, and H. G. Friesen. "Receptors for lactogenic hormones in the ovine corpus luteum. III: Inhibition of 125I-labelled human growth hormone binding by a high molecular weight factor in ovine corpus luteum cytosol." Journal of Endocrinology 114, no. 3 (September 1987): 383–89. http://dx.doi.org/10.1677/joe.0.1140383.

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ABSTRACT Ovine luteal cytosol fractions inhibited the specific binding of 125I-labelled human GH and ovine prolactin (oPRL) to ovine luteal microsomes in a dose-dependent fashion. Inhibition was dependent on divalent cation concentrations, and was abolished by divalent metal ion chelating agents or by boiling. Inhibition was not due to ionic strength or salt effects on hormone binding, the release of endogenously bound oPRL into the cytosol fraction during tissue disruption and fractionation, or the presence of a soluble (or solubilized) lactogenic receptor in ovine cytosol preparations. Gel chromatography of cytosol fractions gave a molecular weight for the inhibitor of approximately 50 000. J. Endocr. (1987) 114, 383–389
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26

Balaghi, M., D. W. Horne, and C. Wagner. "Hepatic one-carbon metabolism in early folate deficiency in rats." Biochemical Journal 291, no. 1 (April 1, 1993): 145–49. http://dx.doi.org/10.1042/bj2910145.

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Glycine N-methyltransferase (GNMT) is inhibited by 5-methyltetrahydrofolate polyglutamate in vitro. It is believed to play a regulatory role in the synthesis de novo of methyl groups. We have used the amino-acid-defined diet of Walzem and Clifford [(1988) J. Nutr. 118, 1089-1096] to determine whether folate deficiency in vivo would affect GNMT activity, as predicted by the studies in vitro. Weanling male rats were fed on the folate-deficient diet or a folate-supplemented diet pair-fed to the deficient group. A third group was fed on the folate-supplemented diet ad libitum. Development of folate deficiency rapidly resulted in decreased levels of S-adenosylmethionine (SAM) and elevation of S-adenosylhomocysteine (SAH). The ratios of SAM to SAH were 1.8, 2.7 and 1.5 in the deficient group for weeks 2, 3 and 4 of the experiment, and the values were 9.7, 7.1 and 8.9 for the pair-fed control group and 10.3, 8.8 and 8.0 for the control group ad libitum fed. The activity of GNMT was significantly higher in the deficient group than in either of the two control groups at each time period. This was not due to increased amounts of GNMT protein, but reflected an increase in specific enzyme activity. Levels of folate in both the cytosol and mitochondria were severely lowered after only 2 weeks on the diet. The distribution of folate coenzymes was also affected by the deficiency, which resulted in a marked increase in the percentage of tetrahydrofolate polyglutamates in both cytosol and mitochondria and a very large decrease in cytosolic 5-methyltetrahydrofolate. The increased GNMT activity is therefore consistent with decreased folate levels and decreased inhibition of enzyme activity.
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27

Stern, P. H., and D. E. Vance. "Phosphatidylcholine metabolism in neonatal mouse calvaria." Biochemical Journal 244, no. 2 (June 1, 1987): 409–15. http://dx.doi.org/10.1042/bj2440409.

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Phosphatidylcholine metabolism was examined in neonatal mouse calvaria in vitro. Incorporation of choline into phosphatidylcholine was slow in this tissue. At 2 h after a pulse of [methyl-3H]choline only 30% of the tissue radioactivity was in the organic phase. Chromatography of the aqueous phase of the tissue extract revealed that more than half of the radioactivity was present as choline at this time. There was no accumulation of phosphocholine, which would have been expected if the cytidylyltransferase were the rate-limiting step in the CDP-choline pathway in the tissue. Choline kinase activity in calvarial cytosol was lower than choline kinase activity in liver cytosol of the same animals. No evidence for significant phosphatidylcholine synthesis through the methylation pathway was found in the calvarial tissue. Although rates of choline-phosphatidylcholine base exchange were higher in bone microsomes than in microsomes from liver, the rate of phosphatidylcholine production through this pathway appeared to be too slow to account for the phosphatidylcholine produced by the calvaria. Phosphatidylcholine synthesis in the calvaria was unaffected by 2 h of treatment with 10 nM-parathyroid hormone, 0.1 nM-0.1 microM-1 alpha,25-dihydroxycholecalciferol, 5 microM-prostaglandin E1 or 2.5 nM-salmon calcitonin, or by 17 h of treatment with 10 nM-parathyroid hormone or 0.1 nM-1 alpha,25-dihydroxycholecalciferol.
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28

Hou, Jin, Gionata Scalcinati, Marco Oldiges, and Goutham N. Vemuri. "Metabolic Impact of Increased NADH Availability in Saccharomyces cerevisiae." Applied and Environmental Microbiology 76, no. 3 (December 18, 2009): 851–59. http://dx.doi.org/10.1128/aem.02040-09.

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ABSTRACT Engineering the level of metabolic cofactors to manipulate metabolic flux is emerging as an attractive strategy for bioprocess applications. We present the metabolic consequences of increasing NADH in the cytosol and the mitochondria of Saccharomyces cerevisiae. In a strain that was disabled in formate metabolism, we either overexpressed the native NAD+-dependent formate dehydrogenase in the cytosol or directed it into the mitochondria by fusing it with the mitochondrial signal sequence encoded by the CYB2 gene. Upon exposure to formate, the mutant strains readily consumed formate and induced fermentative metabolism even under conditions of glucose derepression. Cytosolic overexpression of formate dehydrogenase resulted in the production of glycerol, while when this enzyme was directed into the mitochondria, we observed glycerol and ethanol production. Clearly, these results point toward different patterns of compartmental regulation of redox homeostasis. When pulsed with formate, S. cerevisiae cells growing in a steady state on glucose immediately consumed formate. However, formate consumption ceased after 20 min. Our analysis revealed that metabolites at key branch points of metabolic pathways were affected the most by the genetic perturbations and that the intracellular concentrations of sugar phosphates were specifically affected by time. In conclusion, the results have implications for the design of metabolic networks in yeast for industrial applications.
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29

Dusséaux, Simon, William Thomas Wajn, Yixuan Liu, Codruta Ignea, and Sotirios C. Kampranis. "Transforming yeast peroxisomes into microfactories for the efficient production of high-value isoprenoids." Proceedings of the National Academy of Sciences 117, no. 50 (December 2, 2020): 31789–99. http://dx.doi.org/10.1073/pnas.2013968117.

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Current approaches for the production of high-value compounds in microorganisms mostly use the cytosol as a general reaction vessel. However, competing pathways and metabolic cross-talk frequently prevent efficient synthesis of target compounds in the cytosol. Eukaryotic cells control the complexity of their metabolism by harnessing organelles to insulate biochemical pathways. Inspired by this concept, herein we transform yeast peroxisomes into microfactories for geranyl diphosphate-derived compounds, focusing on monoterpenoids, monoterpene indole alkaloids, and cannabinoids. We introduce a complete mevalonate pathway in the peroxisome to convert acetyl-CoA to several commercially important monoterpenes and achieve up to 125-fold increase over cytosolic production. Furthermore, peroxisomal production improves subsequent decoration by cytochrome P450s, supporting efficient conversion of (S)-(-)-limonene to the menthol precursor trans-isopiperitenol. We also establish synthesis of 8-hydroxygeraniol, the precursor of monoterpene indole alkaloids, and cannabigerolic acid, the cannabinoid precursor. Our findings establish peroxisomal engineering as an efficient strategy for the production of isoprenoids.
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30

Kaye, B., D. J. Rance, and L. Waring. "Oxidative metabolism of carbazeranin vitroby liver cytosol of baboon and man." Xenobiotica 15, no. 3 (January 1985): 237–42. http://dx.doi.org/10.3109/00498258509045354.

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31

Ward, S., and D. J. Back. "Metabolism of gestodene in human liver cytosol and microsomes in vitro." Journal of Steroid Biochemistry and Molecular Biology 46, no. 2 (August 1993): 235–43. http://dx.doi.org/10.1016/0960-0760(93)90299-c.

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32

Kyakumoto, S., R. Kurokawa, Y. Ohara-Nemoto, and M. Ota. "Sex difference in the cytosolic and nuclear distribution of androgen receptor in mouse submandibular gland." Journal of Endocrinology 108, no. 2 (February 1986): 267–73. http://dx.doi.org/10.1677/joe.0.1080267.

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ABSTRACT Cytosol and nuclear androgen receptors in submandibular glands of male and female mice were measured by an exchange assay at 0 °C. The binding of [3H]methyltrienolone to cytosol receptors in females was mostly saturated within a short period of incubation (3 h), whereas the saturation was much slower in males; suggesting that almost all of the cytosol receptors were unoccupied in females and the receptors were partially occupied in males. Nuclear receptors were extracted with pyridoxal 5′-phosphate (5 mmol/l) from nuclear fractions with 93–95% efficiency. The exchange of the bound steroids occurred by 24–48 h at 0 °C, suggesting that most of the nuclear androgen receptor was occupied. The binding was low at higher temperatures, probably due to inactivation of the receptor. Scatchard analysis showed that the apparent dissociation constants of cytosol and nuclear receptors were similar (0·8 and 0·9 nmol/l respectively) in both sexes. On the other hand, the number of androgen-binding sites in the nucleus was much higher in males than in females (1052 fmol/mg DNA and 32 fmol/mg DNA respectively), while the number in the cytosol was higher in females than in males (512 fmol/mg DNA and 368 fmol/mg DNA respectively). These observations show that androgen receptors exist mainly (74%) in the nuclei of males, while they exist mostly (94%) in the cytosol of females. J. Endocr. (1986) 108, 267–273
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33

Agrò, Mauro, and Javier Díaz-Nido. "Effect of Mitochondrial and Cytosolic FXN Isoform Expression on Mitochondrial Dynamics and Metabolism." International Journal of Molecular Sciences 21, no. 21 (November 4, 2020): 8251. http://dx.doi.org/10.3390/ijms21218251.

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Friedreich’s ataxia (FRDA) is a neurodegenerative disease caused by recessive mutations in the frataxin gene that lead to a deficiency of the mitochondrial frataxin (FXN) protein. Alternative forms of frataxin have been described, with different cellular localization and tissue distribution, including a cerebellum-specific cytosolic isoform called FXN II. Here, we explored the functional roles of FXN II in comparison to the mitochondrial FXN I isoform, highlighting the existence of potential cross-talk between cellular compartments. To achieve this, we transduced two human cell lines of patient and healthy subjects with lentiviral vectors overexpressing the mitochondrial or the cytosolic FXN isoforms and studied their effect on the mitochondrial network and metabolism. We confirmed the cytosolic localization of FXN isoform II in our in vitro models. Interestingly, both cytosolic and mitochondrial isoforms have an effect on mitochondrial dynamics, affecting different parameters. Accordingly, increases of mitochondrial respiration were detected after transduction with FXN I or FXN II in both cellular models. Together, these results point to the existence of a potential cross-talk mechanism between the cytosol and mitochondria, mediated by FXN isoforms. A more thorough knowledge of the mechanisms of action behind the extra-mitochondrial FXN II isoform could prove useful in unraveling FRDA physiopathology.
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34

Cho, Yong-Gu, and Kwon-Kyoo Kang. "Functional Analysis of Starch Metabolism in Plants." Plants 9, no. 9 (September 6, 2020): 1152. http://dx.doi.org/10.3390/plants9091152.

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In plants, starch is synthesized in leaves during the day-time from fixed carbon through photosynthesis and is mobilized at night to support continued respiration, sucrose export, and growth in the dark. The main crops where starch is biosynthesized and stored are corn, rice, wheat, and potatoes, and they are mainly used as food resources for humankind. There are many genes that are involved in starch biosynthesis from cytosol to storage organs in plants. ADP-glucose, UDP- glucose, and glucose-6-phosphate are synthesized catalyzed by UDP-invertase, AGPase, hexokinase, and P- hexose-isomerase in cytosol. Starch composed of amylopectin and amylose is synthesized by starch synthase, granule bound starch synthase, starch-branching enzyme, debranching enzyme, and pullulanase, which is primarily responsible for starch production in storage organs. Recently, it has been uncovered that structural genes are controlled by proteins derived from other genes such as transcription factors. To obtain more precise information on starch metabolism, the functions of genes and transcription factors need to be studied to understand their roles and functions in starch biosynthesis in plants. However, the roles of genes related to starch biosynthesis are not yet clearly understood. The papers of this special issue contain reviews and research articles on these topics and will be a useful resource for researchers involved in the quality improvement of starch storage crops.
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35

Thieulant, Marie-Lise, and Jean Pelletier. "Oestradiol binding to nuclei of anterior pituitary cells of the ram." Acta Endocrinologica 109, no. 1 (May 1985): 50–57. http://dx.doi.org/10.1530/acta.0.1090050.

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Abstract. The methodology to fully characterise nuclear receptor for oestradiol-17β (E2) in the ram pituitary has been investigated. Purified nuclei, clean under the electron microscope, were obtained from 2.4 m sucrose ultracentrifugation and were extracted for 2 h at 0°C with 0.6 m NaCl. After centrifugation, the supernatant was incubated with [3H]E2 with or without a 100-fold excess of unlabelled E2. The main results were: the specific binding was maximum at 20°C in 2–3 h and remained constant up to 19 h without significant metabolism; an incubation temperature of 25°C reduces the binding, while at 0°C maximum binding was attained at a much slower rate; the binding was linearly related to the dose of nuclear proteins; the binding was not affected by DNase and RNase but was suppressed by trypsin, pronase or a temperature of 56°C; binding was specific for oestrogens; preincubation of cytosol with [3H]E2 and then coincubation with nuclei showed an uptake of the [3H]E2 receptor complex by nuclei; such a transfer was inhibited if cytosol was previously heated; after a prelabelled cytosol-nuclei coincubation, a specific binding peak was found in the nuclear extract submitted to sucrose gradient sedimentation (4.1S); in vivo injection of 100 μg E2 resulted in a sharp increase in nuclear receptor numbers 30 and 60 min later, with a concomitant drop in cytosolic receptor numbers. These results indicate that E2 can bind to pituitary nuclei in the ram.
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36

Daniel, Trnka, Hossain Md Faruq, Jordt Laura Magdalena, Gellert Manuela, and Lillig Christopher Horst. "Role of GSH and Iron-Sulfur Glutaredoxins in Iron Metabolism—Review." Molecules 25, no. 17 (August 25, 2020): 3860. http://dx.doi.org/10.3390/molecules25173860.

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Glutathione (GSH) was initially identified and characterized for its redox properties and later for its contributions to detoxification reactions. Over the past decade, however, the essential contributions of glutathione to cellular iron metabolism have come more and more into focus. GSH is indispensable in mitochondrial iron-sulfur (FeS) cluster biosynthesis, primarily by co-ligating FeS clusters as a cofactor of the CGFS-type (class II) glutaredoxins (Grxs). GSH is required for the export of the yet to be defined FeS precursor from the mitochondria to the cytosol. In the cytosol, it is an essential cofactor, again of the multi-domain CGFS-type Grxs, master players in cellular iron and FeS trafficking. In this review, we summarize the recent advances and progress in this field. The most urgent open questions are discussed, such as the role of GSH in the export of FeS precursors from mitochondria, the physiological roles of the CGFS-type Grx interactions with BolA-like proteins and the cluster transfer between Grxs and recipient proteins.
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37

Isomaa, Veli, Mauri Orava, and Reijo Vihko. "Evidence for an androgen receptor in porcine Leydig cells." Acta Endocrinologica 115, no. 1 (May 1987): 119–24. http://dx.doi.org/10.1530/acta.0.1150119.

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Abstract. Cytosol and nuclear androgen receptor concentrations were measured in freshly prepared and cultured Leydig cells of immature pig testis with exchange assays using [3H]methyltrienolone as labelled ligand. Androgen receptors in Leydig cells had high affinity for [3H]methyltrienolone and steroid binding specificity typical of an androgen receptor. The mean receptor concentrations were 76 fmol/mg protein and 210 fmol/mg DNA for cytosol and nuclei, respectively. In sucrose gradients, cytosol androgen receptors sedimented in the 4 S region. The cells maintained androgen receptors under culture conditions. Exposure of cultured cells to [3H]methyltrienolone (10 nmol/l) resulted in accumulation of androgen receptors in the nuclei with maximal uptake by 1 h. We conclude that methyltrienolone binding sites with characteristics of androgen receptors were identified in both cytosol and nuclei of porcine Leydig cells.
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38

Takahashi, T., T. Yamaguchi, M. Shitashige, T. Okamoto, and T. Kishi. "Reduction of ubiquinone in membrane lipids by rat liver cytosol and its involvement in the cellular defence system against lipid peroxidation." Biochemical Journal 309, no. 3 (August 1, 1995): 883–90. http://dx.doi.org/10.1042/bj3090883.

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Rat liver homogenates reduced ubiquinone (UQ)-10 to ubiquinol (UQH2)-10 in the presence of NADPH rather than NADH. This NADPH-dependent UQ reductase (NADPH-UQ reductase) activity that was not inhibited by antimycin A and rotenone, was located mainly in the cytosol fraction and its activity accounted for 68% of that of the homogenates. Furthermore, the NADPH-UQ reductase from rat liver cytosol efficiently reduced both UQ-10 incorporated into egg yolk lecithin liposomes, and native UQ-9 residing in rat microsomes, to the respective UQH2 form in the presence of NADPH. The gross redox ratios of UQH2-9/(UQ-9 + UQH2-9) in individual tissues of rat correlated positively with the log of their respective cytosolic NADPH-UQ reductase activities, while the redox ratios in every intracellular fraction from liver were at about the same level, irrespective of NADPH-UQ reductase activities in the respective fractions. The combined addition of rat liver cytosol and NADPH inhibited to a great extent 2,2′-azobis(2,4-dimethyl-valeronitrile)-induced lipid peroxidation of UQ-10-fortified lecithin liposomes and completely inhibited such peroxidation in the liposomes in which UQH2-10 replaced UQ-10. The NADPH-UQ reductase activity was clearly separated from DT-diaphorase (EC 1.6.99.2) activity by means of Cibacron Blue-immobilized Bio-Gel A-5m chromatography. In conclusion, the NADPH-UQ reductase in cytosol, which is a novel enzyme to our knowledge, was presumed to be responsible for maintaining the steady-state redox levels of intracellular UQ and thereby to act as an endogenous antioxidant in protecting intracellular membranes from lipid peroxidation that is inevitably induced in aerobic metabolism.
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39

Sheflin, Lowell G., and Stephen W. Spaulding. "Testosterone and dihydrotestosterone regulate AUF1 isoforms in a tissue-specific fashion in the mouse." American Journal of Physiology-Endocrinology and Metabolism 278, no. 1 (January 1, 2000): E50—E57. http://dx.doi.org/10.1152/ajpendo.2000.278.1.e50.

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.—The sex difference in the metabolism of certain mRNAs in the murine submaxillary gland (SMG) prompted us to determine whether androgens regulate the expression of any of the four isoforms of AUF1, proteins that bind differentially to AU-rich RNA. We found that cytosol from female SMGs contains two major isoforms (p45 and p40), whereas cytosol from male SMGs contains a prominent p37 and a weaker p42. Injecting female mice with testosterone decreases p45 levels by 81% after 7 days ( P < 0.05, n = 4), whereas p42 and p37 increase 74 and 449% at 7 days ( P < 0.05, n = 4, for both). Orchiectomy, conversely, decreases p37 levels in the male SMG by 91% ( P < 0.006) while increasing p45 5-fold and p40 2.5-fold ( P < 0.05, n = 5 for both). Both male and female kidney cytosol contains a prominent p37 and a faint band of ∼42 kDa, but neither shows a significant change when circulating androgen levels are altered. Dihydrotestosterone (DHT) changes the pattern of AUF1 isoforms in female SMG cytosol more rapidly than does testosterone. Nuclear extracts from female SMG contain predominantly p45, and DHT decreases its level slightly (35%, P < 0.05 at 24 h). Polysomal extracts from female SMG contain p45 and p42, and DHT increases p45 levels 58% ( P < 0.02, n = 6) at 24 h. In certain nonreproductive tissues, androgens may differentially regulate AUF1 isoform levels to modulate the metabolism of AU-rich mRNAs posttranscriptionally.
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40

Lewis, Caroline A., Seth J. Parker, Brian P. Fiske, Douglas McCloskey, Dan Y. Gui, Courtney R. Green, Natalie I. Vokes, Adam M. Feist, Matthew G. Vander Heiden, and Christian M. Metallo. "Tracing Compartmentalized NADPH Metabolism in the Cytosol and Mitochondria of Mammalian Cells." Molecular Cell 55, no. 2 (July 2014): 253–63. http://dx.doi.org/10.1016/j.molcel.2014.05.008.

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41

Kaur, Kamaljeet, and Rangil Singh. "Sugar metabolism and partitioning in cytosol and bacteroid fractions of chickpea nodules." Plant Physiology and Biochemistry 37, no. 9 (September 1999): 685–92. http://dx.doi.org/10.1016/s0981-9428(00)80099-6.

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42

Tulayakul, Phitsanu, Kesu Dong, and Susumu Kumagai. "Organ differences in microsomes and cytosol metabolism of Aflatoxin B1 in piglets." Toxicological & Environmental Chemistry 88, no. 3 (July 2006): 479–87. http://dx.doi.org/10.1080/02772240600662203.

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43

Tsushima, Keizo. "Properties of cytosol 5′-nucleotidase and its role in purine nucleotide metabolism." Advances in Enzyme Regulation 25 (January 1986): 181–200. http://dx.doi.org/10.1016/0065-2571(86)90014-2.

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44

Castro, GD, MH Costantini, and JA Castro. "Rat ventral prostate xanthine oxidase–mediated metabolism of acetaldehyde to acetyl radical." Human & Experimental Toxicology 28, no. 4 (April 2009): 203–8. http://dx.doi.org/10.1177/0960327109105406.

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Alcohol drinking is known to lead to deleterious effects on prostate epithelial cells from humans and experimental animals. The understanding of the mechanisms underlying these effects is relevant to intraprostatic ethanol treatment of benign prostatic hyperplasia and to shed some light into the conflictive results linking alcohol consumption to prostate cancer. In previous studies, we provided evidence about the presence in the rat ventral prostate of cytosolic and microsomal metabolic pathways of ethanol to acetaldehyde and 1-hydroxyethyl radical and about the low levels of alcohol dehydrogenase and aldehyde dehydrogenase. Acetaldehyde accumulation in prostate tissue and oxidative stress promotion were also observed. In this study, we report that in the ventral prostate cytosolic fraction, xanthine oxidoreductase is able to metabolize acetaldehyde to acetyl radical. The identification of the acetyl was performed by GC-MS of the silylated acetyl-PBN adduct. Reference adduct was generated chemically. Formation of acetyl was also observed using pure xanthine oxidase. The generation of acetyl by the prostate cytosol was inhibited by allopurinol, oxypurinol, diphenyleneiodonium chloride, folate, and ellagic acid. Results suggest that metabolism of ethanol to acetaldehyde and to 1-hydroxyethyl and acetyl radicals could be involved in the deleterious effects of alcohol drinking on prostate epithelial cells.
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45

Nilsson, Avlant, Jurgen R. Haanstra, Martin Engqvist, Albert Gerding, Barbara M. Bakker, Ursula Klingmüller, Bas Teusink, and Jens Nielsen. "Quantitative analysis of amino acid metabolism in liver cancer links glutamate excretion to nucleotide synthesis." Proceedings of the National Academy of Sciences 117, no. 19 (April 27, 2020): 10294–304. http://dx.doi.org/10.1073/pnas.1919250117.

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Many cancer cells consume glutamine at high rates; counterintuitively, they simultaneously excrete glutamate, the first intermediate in glutamine metabolism. Glutamine consumption has been linked to replenishment of tricarboxylic acid cycle (TCA) intermediates and synthesis of adenosine triphosphate (ATP), but the reason for glutamate excretion is unclear. Here, we dynamically profile the uptake and excretion fluxes of a liver cancer cell line (HepG2) and use genome-scale metabolic modeling for in-depth analysis. We find that up to 30% of the glutamine is metabolized in the cytosol, primarily for nucleotide synthesis, producing cytosolic glutamate. We hypothesize that excreting glutamate helps the cell to increase the nucleotide synthesis rate to sustain growth. Indeed, we show experimentally that partial inhibition of glutamate excretion reduces cell growth. Our integrative approach thus links glutamine addiction to glutamate excretion in cancer and points toward potential drug targets.
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46

Altschuler, L. R., J. A. Ceppi, M. N. Ritta, R. S. Calandra, and A. A. Zaninovich. "Effects of thyroxine on oestrogen receptor concentrations in anterior pituitary and hypothalamus of hypothyroid rats." Journal of Endocrinology 119, no. 3 (December 1988): 383–87. http://dx.doi.org/10.1677/joe.0.1190383.

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ABSTRACT The effects of thyroxine (T4) were studied on the concentration of oestrogen receptors in the anterior pituitary gland and hypothalamus of ovariectomized euthyroid and hypothyroid rats. A group of rats was made hypothyroid by the administration of I. Seven days after ovariectomy, animals were separated into five groups: I, euthyroid controls; II, hypothyroid controls; III, hypothyroid and injected with oestradiol benzoate (10 μg/day for 10 days); IV, hypothyroid and injected with T4 (4 μg/day for 10 days) and V, hypothyroid and injected with both oestradiol and T4 as described above. In group I, oestrogen receptor levels in pituitary cytosol were 44·4 ± 3·4 (s.d.) fmol/mg protein and in the nucleus 47·7 ± 4·0 fmol/mg DNA. In group II the respective values were 12·8 ± 1·7 fmol/mg protein (P <0·01) and 12·7 ± 1·7 fmol/mg DNA (P <0·01 compared with group I). In group III, cytosolic receptor concentrations decreased when compared with those in group II (P <0·05), whereas nuclear receptor concentrations rose significantly (P <0·01). Group IV had both pituitary cytosolic and nuclear receptors increased (P <0·01 compared with group II). In group V there were no changes in cytosolic receptor concentrations but a significant (P <0·01) rise in nuclear receptors as compared with group II. Hypothalamic oestrogen receptors in untreated hypothyroid rats (group II) were unchanged in the cytosol and diminished (P <0·01) in the nucleus in relation to euthyroid controls (group I). Thyroxine, but not oestrogen, was effective in increasing the concentration of cytosolic receptors (P <0·05). Neither hormone caused changes in nuclei. The results show that there is a pronounced decrease in pituitary and hypothalamic (nuclei) oestrogen receptors in untreated hypothyroid rats and that this decrease can be reversed by T4 treatment. J. Endocr. (1988) 119, 383–387
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47

Elliott, Robert L., Fen Wang, Mary C. Elliott, and Jonathan F. Head. "An immunocytochemical, cytosol, and ultrastructural study of tissue ferritin in breast carcinoma." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 298–99. http://dx.doi.org/10.1017/s0424820100169225.

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Increased levels of serum ferritin in breast carcinoma is well known, however, its exact source has been disputed. Weinstein et al found six times the ferritin concentration in malignant tissue as compared to benign tissue. The anaplastic tumors had the highest ferritin concentrations, suggesting that the major site of the increased ferritin was the malignant epithelium. We found in a previous cytosolic and electron microscopic study of tissue ferritin in breast carcinoma that the malignant epithelium is almost certainly the source of the increased ferritin.To better define and expand this study and increase our knowledge of the role of transferrin receptors and iron metabolism in breast cancer, we began an immunocytochemical study of tissue ferritin to compliment our cytosol and ultrastructural observations. This was done with a mouse antihuman ferritin monoclonal antibody. To date 92 specimens have been examined by all three techniques. Immunocytochemical tissue slides showed intense staining of the cytoplasm with immunoperoxidase, and the intensity of the cytoplasmic staining correlated with the cytosolic concentrations and the electron microscopic findings.
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48

Pedersen, Henrik, Morten Carlsen, and Jens Nielsen. "Identification of Enzymes and Quantification of Metabolic Fluxes in the Wild Type and in a Recombinant Aspergillus oryzae Strain." Applied and Environmental Microbiology 65, no. 1 (January 1, 1999): 11–19. http://dx.doi.org/10.1128/aem.65.1.11-19.1999.

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ABSTRACT Two α-amylase-producing strains of Aspergillus oryzae, a wild-type strain and a recombinant containing additional copies of the α-amylase gene, were characterized with respect to enzyme activities, localization of enzymes to the mitochondria or cytosol, macromolecular composition, and metabolic fluxes through the central metabolism during glucose-limited chemostat cultivations. Citrate synthase and isocitrate dehydrogenase (NAD) activities were found only in the mitochondria, glucose-6-phosphate dehydrogenase and glutamate dehydrogenase (NADP) activities were found only in the cytosol, and isocitrate dehydrogenase (NADP), glutamate oxaloacetate transaminase, malate dehydrogenase, and glutamate dehydrogenase (NAD) activities were found in both the mitochondria and the cytosol. The measured biomass components and ash could account for 95% (wt/wt) of the biomass. The protein and RNA contents increased linearly with increasing specific growth rate, but the carbohydrate and chitin contents decreased. A metabolic model consisting of 69 fluxes and 59 intracellular metabolites was used to calculate the metabolic fluxes through the central metabolism at several specific growth rates, with ammonia or nitrate as the nitrogen source. The flux through the pentose phosphate pathway increased with increasing specific growth rate. The fluxes through the pentose phosphate pathway were 15 to 26% higher for the recombinant strain than for the wild-type strain.
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49

Herington, A. C., J. L. Stevenson, and S. I. Ymer. "Binding proteins for growth hormone and prolactin in rabbit kidney cytosol." American Journal of Physiology-Endocrinology and Metabolism 255, no. 3 (September 1, 1988): E293—E298. http://dx.doi.org/10.1152/ajpendo.1988.255.3.e293.

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Two soluble, receptor-like binding proteins with apparent somatotrophic [growth hormone (GH)] and lactogenic [prolactin (PRL)] specificities, respectively, and that are present in rabbit kidney cytosol have now been examined in more detail using specific GH receptor and PRL receptor monoclonal antibodies (MAb). Gel chromatography of 125I-labeled human GH (125I-hGH) kidney cytosol complexes in the absence of these MAbs revealed two specifically bound regions of radioactivity at molecular weights (MW) of approximately 120,000 and approximately 60,000, which are similar in size to complexes formed by the native GH receptor of rabbit liver cytosol and the PRL receptor of mammary gland. Co-incubation with GH-receptor MAb inhibited 125I-hGH binding only to the higher MW (120,000) species, whereas the PRL-receptor MAb inhibited only the lower MW (60,000) species, thus establishing definitively the hormonal specificities of the two binding proteins. The presence of both GH- and PRL-specific binding subunits in cytosol was confirmed using covalent cross-linking techniques. No GH binding protein was detected in kidney membranes. The presence of naturally soluble, receptor-like binding proteins for GH and PRL in kidney cytosol preparations raises the possibility of their playing a role in the intracellular regulation of kidney function and/or metabolism.
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50

Shelp, Barry J., Gale G. Bozzo, Christopher P. Trobacher, Greta Chiu, and Vikramjit S. Bajwa. "Strategies and tools for studying the metabolism and function of γ-aminobutyrate in plants. I. Pathway structure." Botany 90, no. 8 (August 2012): 651–68. http://dx.doi.org/10.1139/b2012-030.

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γ-Aminobutyrate (GABA) is a ubiquitous four-C, nonprotein, amino acid that has been linked to stress, signaling, and storage in plants. In this paper, we discuss analytical, enzyme-linked, and colorimetric methods for analyzing GABA and related metabolites, and review tracer evidence for the derivation of GABA from glutamate and its subsequent catabolism to succinic semialdehyde and either succinate or γ-hydroxybutyrate. Also, we describe biochemical, complementation, bioinformatic, recombinant, and modelling strategies for identifying genes and investigating properties of the encoded proteins responsible for transport and metabolism of GABA. For Arabidopsis, evidence supports the involvement of a plasma membrane GABA transporter, a mitochondrial GABA permease, a cytosolic Ca2+/calmodulin- and pH-regulated cytosolic glutamate decarboxylase, a pyruvate- and glyoxylate-regulated mitochondrial GABA transaminase, a redox-regulated mitochondrial succinic semialdehyde dehydrogenase, and redox-regulated glyoxylate/succinic semialdehyde reductases located in both cytosol and plastid, respectively. This simple biochemical model does not account for species and tissue differences in the isoform complement of GABA pathway enzymes or transcriptional control of the pathway. In a companion review, we provide a more integrated view of GABA metabolism and function.
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