The Role of Phosphorylation in the Regulation of Acetyl-CoA Carboxylase Activity by Insulin and other Hormones
Insulin stimulates fatty acid synthesis in adipose and other tissues by increasing acetyl-CoA carboxylase activity. 1,2,3,4,5 epididymal fat cells and liver cells this activation is associated with increased phosphorylation of the enzyme at specific sites, particularly within a peptide designated the I-peptide. 6,7,8,9 Inhibition of fatty acid synthesis by hormones such as adrenaline and glucagon involves decreases in acetyl-CoA carboxylase activity. Inhibition is also associated with increased phosphorylation of the enzyme however at sites distinct from those found after insulin treatment. There is good evidence that the adrenaline and glucagon stimulated phosphorylation of the enzyme is carried out by cyclic AMP- dependent protein kinase 10,8,11,12 whereas the insulin stimulated phosphorylation is carried out by an as yet uncharacterised cyclic AMP-independent protein kinase.
KeywordsFatty Acid Synthesis Concentrate Extract Pyruvate Carboxylase Potassium Citrate Fatty Acid Synthetase
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