Purification and properties of a kinase which phosphorylates and inactivates acetyl-CoA carboxylase.
A protein kinase which phosphorylates and inactivates acetyl-CoA carboxylase has been purified to apparent homogeneity from rat liver. The kinase was found to exist in two forms: bound to carboxylase in a complex or in a free form that is in different stages of aggregation over a wide range of molecular weights. The purification of the kinase involved first partial purification of acetyl-CoA carboxylase through polyethylene glycol precipitation and DEAE-cellulose chromatography. The kinase was then separated from acetyl-CoA carboxylase by Sepharose 2B chromatography. The molecular weight of the kinase subunit was 170,000 as determined by sodium dodecyl sulfate-gel electrophoresis. The incorporation of 1 mol of phosphate/mole of carboxylase subunit caused complete inactivation of the carboxylase. Acetyl-CoA carboxylase, inactivated by the kinase, can be dephosphorylated and reactivated when incubated with phosphorylase phosphatase. The Km values of the kinase for acetyl-CoA carboxylase and ATP are 90 nM and 20 microM, respectively. The kinase was found to be cyclic AMP-independent, but activated by CoA. The protein kinase can phosphorylate acetyl-CoA carboxylase, protamine, and histones, but could not act on hydroxymethylglutaryl-CoA reductase or phosphorylase b.
D000103:Acetyl-CoA Carboxylase / Q000037:antagonists & inhibitors*; D000818:Animals; D007700:Kinetics; D008025:Ligases / Q000037:antagonists & inhibitors*; D008099:Liver / Q000201:enzymology*; D008970:Molecular Weight; D010766:Phosphorylation; D011494:Protein Kinases / Q000302:isolation & purification* / Q000378:metabolism; D051381:Rats; D013379:Substrate Specificity
D011494:Protein Kinases; C033288:(acetyl-CoA carboxylase) kinase; D008025:Ligases; D000103:Acetyl-CoA Carboxylase