Yeast acetyl-CoA carboxylase: in vitro phosphorylation by mammalian and yeast protein kinases.
Acetyl-CoA carboxylase (ACC) is regulated in mammalian tissues, in part, by multisite enzyme phosphorylation. Yeast ACC (Y-ACC) has been highly purified from S. cerevisiae by monomeric avidin-Sepharose chromatography, revealing an enzyme subunit species of molecular mass 265,000 Da. Unlike mammalian enzyme, Y-ACC is citrate-independent, and reacts weakly or not at all with a panel of anti-rat liver ACC antibodies. Like rat ACC, Y-ACC is rapidly phosphorylated and inactivated by two mammalian carboxylase kinases, the cAMP-dependent protein kinase and 5'-AMP-stimulated kinase. It is also phosphorylated by rat liver casein kinase II, but without any change in catalytic activity. Three major yeast protein kinases active on ACC have been fractionated; all co-elute with kinases active on casein, but each appears to be a distinct catalytic species. Like the mammalian casein kinases, however, phosphorylation of ACC by these yeast kinases does not alter yeast ACC activity. Taken together, these data indicate that Y-ACC possesses at least two classes of phosphorylation sites, one or more of which acutely regulates enzyme activity. Alterations in Y-ACC phosphorylation in yeast, as in mammalian tissues, could be an important modulator of the rates of fatty acid synthesis.
Witters
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LA
Department of Medicine, Dartmouth Medical School, Hanover, NH 03756.
Watts
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TD
D000103:Acetyl-CoA Carboxylase / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D007700:Kinetics; D008025:Ligases / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008297:Male; D008970:Molecular Weight; D010766:Phosphorylation; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013379:Substrate Specificity
D011494:Protein Kinases; D008025:Ligases; D000103:Acetyl-CoA Carboxylase