Acetyl-CoA Carboxylase
Acetyl-CoA carboxylase is the primary regulatory enzyme in fatty acid biosynthesis. The active form of the enzyme is a long filamentous array of monomer units. Monomeric units can be either phosphorylated (polymer not favored) or dephosphorylated (polymer formation favored).
Acetyl-CoA carboxylase can be phosphorylated by two kinases, cAMP-dependent protein kinase or AMP-dependent protein kinase.
The enzyme catalyzes the addition of a carboxyl group from bicarbonate to acetyl-CoA, forming malonyl-CoA.
Acetyl-CoA + ATP + HCO3- <=> Malonyl-CoA + ADP + Pi + H+
Like other carboxylases, acetyl-CoA carboxylase contains a biotin cofactor.