Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.4.1.2 (acetyl-CoA carboxylase)
 2,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism of the vitamin K-dependent post-translational carboxylation of the gamma-carbon atom of glutamic acid residues in proteins remains obscure. Experiments were performed in vivo and in vitro in an attempt to establish a role for biotin in the transfer of the carboxyl group. Weanling male rats were fed on a biotin-deficient diet until severe biotin deficiency was induced. Their degree of biotin deficiency was documented by assaying for liver acetyl-CoA carboxylase activity, which was about 15% of normal. However, one-stage and two-stage prothrombin times measured on the plasmas were normal. In addition, the liver microsomal fraction did not contain any more prothrombin precursor than did that of normal rat liver. Experiments were done in vitro in which vitamin K-dependent fixing of 14CO2 was measured in the liver microsomal fraction from vitamin K-deficient male rats in the presence or absence of avidin. No evidence for an avidin-sensitive critical biotin-containing site was obtained. Thus neither series of experiments suggests a role for biotin; the data are compatible with carboxyl transfer occurring either through a carboxylated vitamin K intermediate; or via a yet to be identified intermediate, or perhaps via CO2 itself.
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PMID:The apparent absence of involvement of biotin in the vitamin K-dependent carboxylation of glutamic acid residues of proteins. 1 95

Effect of citrate on acetyl-CoA incorporation into mevalonic acid, sterols and fatty acids after preliminary incubation of rat liver extracts under conditions optimal for acetyl-CoA carboxylase activation, was studied. 30 min preincubation with the citrate at 37 degrees C results in a 2--3-fold stimulation of the mevalonic acid biosynthesis from acetyl-CoA in the microsomal and soluble (140 000 g) fraction, and in that of sterols precipitated by digitonin or isolated by TLC in the mitochondria--free fraction. 2-14C-malonyl-CoA incorporation into the mevalonic acid and sterols and biosynthesis of sterols from 2-14C-mevalonic acid were not stimulated under those conditions. A correlation was shown to exist between the activity of acetyl-CoA carboxylase and the rate of acetyl-CoA incorporation into mevalonate and sterols; the activity of beta-hydroxy-beta-methylglutaryl-CoA reductase, limiting the rate of the sterol biosynthesis, was not changed. The stimulating effect of citrate was found to depend on the concentration of acetyl-CoA and NADPH in the medium. The data obtained suggest that the mevalonic acid biosynthesis in rat liver may occur in the presence of acetyl-CoA carboxylase through the formation of malonyl-CoA.
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PMID:[Possible role of acetyl-CoA-carboxylase in biosynthesis of mevalonic acid and sterols in rat liver]. 1 34

Plasma insulin concentrations in cold-adapted rats were altered acutely by administration of glucose or anti-insulin serum. Rates of fatty acid synthesis in interscapular brown adipose tissue were determined from the incorporation of 3H from 3H2O into tissue lipid. Rates of synthesis were greatly elevated after glucose administration and markedly decreased after injection with anti-insulin serum. Parallel changes in the initial activities of both acetyl-CoA carboxylase and pyruvate dehydrogenase were observed under these conditions, but no changes in total activities were evident. The results suggest that this tissue is an important site of fatty acid synthesis in the cold-adapted rat and that this feature of the tissue is sensitive to changes in plasma insulin concentrations.
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PMID:Evidence that fatty acid synthesis in the interscapular brown adipose tissue of cold-adapted rats is increased in vivo by insulin by mechanisms involving parallel activation of pyruvate dehydrogenase and acetyl-coenzyme A carboxylase. 2 6

Plasma cholesterol was lower in spontaneously hypertensive rats (SHR), while plasma triglyceride and free fatty acid were increased in comparison with control normotensive Wistar-Kyoto (WK) rats. Correspondingly, [1-14C]-acetate incorporation into liver cholesterol was clearly decreased in SHR as compared with WK. As for lipogenic enzyme activities, glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase in SHR were respectively decreased, increased and not significantly different, in comparison with WK rats. Liver cholesterol was rather low and cardiac triglyceride was slightly increased in SHR. Aortic cholesterol and triglyceride levels were not significantly different between SHR AND WK rats. Thus, SHR have an abnormality in lipid metabolism, especially in cholesterol synthesis, but the pathological implication of this in hypertension and related vascular lesions is not yet clear.
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PMID:Lipid metabolism in spontaneously hypertensive rats (SHR). 2 30

Intact rat epididymal fat-cells were incubated with 32Pi and the intracellular proteins separated by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. One of the phosphorylated proteins has the same RF value as [14C]biotin-labelled acetyl-CoA carboxylase purified from fat-cells and is specifically precipitated after incubation with antiserum raised against acetyl-CoA carboxylase. No significant changes in the extent of phosphorylation of acetyl-CoA carboxylase were detected after exposure of the cells to insulin.
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PMID:Demonstration of the phosphorylation of acetyl-coenzyme A carboxylase within intact rat epididymal fat-cells. 2 37

Partially purified acetyl-CoA carboxylase was covalently bound to a Sepharose 4B matrix. Although aggregation was thus prevented, the enzymic activity was stimulated by citrate and isocitrate.
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PMID:Activation of immobilized acetyl-Coenzyme A carboxylase. 2 39

1. Synthesis de novo of fatty acids in the rat liver, measured per g wet wt. of tissue, was increased by a factor of about two, between 1 and 4 days after partial hepatectomy, compared with rates in sham-operated control rat livers. 2. There were no associated changes in the rates of liver cholesterol synthesis or of adipose-tissue fatty acid synthesis in rats after partial hepatectomy, compared with rates in sham-operated rats. 3. In regenerating livers, perfused under three different conditions, there was no alteration in the capacity for fatty acid synthesis compared with that of control rats. 4. The increased synthesis of fatty acids in regenerating liver was associated with insignificant increases in plasma concentrations of tricylglycerols and free fatty acids, with a decrease in content of liver glycogen, and with no change in hepatic activity of acetyl-CoA carboxylase. 5. The accelerated rate of synthesis of fatty adids in regenerating liver appears not to be due to any intrinsic alteration in hepatic capacity for fatty acid synthesis, but it may be caused by the continuous action on liver of unidentified circulating factors.
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PMID:Fatty acid synthesis in the regenerating liver of the rat. 2 43

Digitonin treatment of chick liver cells in monolayer culture perforates the plasma membrane, causing release of acetyl-CoA carboxylase and other cytosolic enzymes. The rate of carboxylase release is affected by conditions known to alter the position of the protomer-polymer (filament) equilibrium of the enzyme. Citrate, an allosteric activator of the carboxylase, induces polymerization of the protomeric avidin-sensitive form giving rise to the avidin-insensitive polymeric filamentous form. When cells are exposed to N6,O2-dibutyryl cyclic adenosine 3':5'-monophosphate which lowers intracellular citrate levels, the rate of carboxylase release from digitonin-treated cells is greatly accelerated. The presence of avidin, which rapidly enters the cell during digitonin treatment, inactivates carboxylase under conditions that promote depolymerization and rapid release, but not under conditions which promote polymerization and slow release. These findings indicate that carboxylase filaments exist in the intact chick liver cell when the cytoplasmic citrate level is high and undergo depolymerization when citrate levels fall.
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PMID:Acetyl-CoA carboxylase. Evidence for polymeric filament to protomer transition in the intact avian liver cell. 2 87

Acetyl-CoA carboxylase in rat liver homogenates was activated in vitro in a time- and temperature-dependent manner. The activity of acetyl-CoA carboxylase in rat liver preparations was determined in a 1-min assay to preclude the possibility of citrate activation of the enzyme during the assay period. Activation of the enzyme occurred more rapidly in liver preparations continuously maintained at ambient or greater temperatures than in homogenates of liver which had been chilled. High speed supernatant (105,000 X g, 60 min) did not heat-activate, and reconstitution of the heat-activatable 27,000 X g, 20-min, fraction by recombining the high speed pellet with the high speed supernatant only partially restored the heat activatability. Elution of the 105,000 X g supernatant from Sephadex G-25 resulted in an enzyme preparation which was heat-activatable. Addition of boiled 105,000 X g supernatant to the Sephadex G-25-treated enzyme again prevented heat activation. Dilution of the enzyme 5-fold did not prevent heat activation.
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PMID:Heat activation of rat liver acetyl-CoA carboxylase in vitro. 2 6

When chick liver cells in monolayer culture were incubated with 32Pi in the presence of insulin, acetyl-CoA carboxylase became extensively labeled with 32Pi reaching a stoichiometry of 9 to 10 mol of phosphoryl group per mol of 240,000-dalton enzyme subunit. The covalently bound phosphate was found to be metabolically labile, turning over with a t1/2 of approximately 2 h (enzyme t1/2 approximately equal to 24 h). Addition of Bt2cAMP altered neither the rate nor extent of phosphorylation. Contrary to other reports, the fully phosphorylated acetyl-CoA carboxylase appears to be catalytically active.
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PMID:Multiple phosphorylation of acetyl-CoA carboxylase in chick liver cells. A cyclic AMP-independent process. 2 15


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