Which of the following enzymes is most responsive to changes in the level of circulating insulin such that as insulin levels rise fatty acid synthesis is increased?
A) acetyl-CoA carboxylase
B) ATP-citrate lyase
C) fatty acid synthase
D) malonyl-CoA decarboxylase
E) steroyl-CoA desaturase

Question

Quizplus · Accepted Answer

Acetyl-CoA carboxylase is the rate-limiting enzyme in fatty acid synthesis and is activated by insulin. When insulin levels rise, it promotes the dephosphorylation and activation of acetyl-CoA carboxylase, leading to increased fatty acid synthesis.  ACC activity is inhibited by phosphorylation. Both ACC1 and ACC2 undergo phosphorylation. Glucagon-stimulated increases in cAMP and subsequently to increased PKA activity lead to phosphorylation and inhibition of ACC. The activating effects of insulin on ACC are complex but are, in part, related to reductions in cAMP levels via the insulinmediated activation of phosphodiesterase.

Which of the Following Enzymes Is Most Responsive to Changes