Acetyl-CoA carboxylase (ACC) is a complex multifunctional enzyme system. ACC is a biotin-containing enzyme which catalyzes the carboxylation of acetyl-CoA to malonyl-CoA, the rate-limiting step in fatty acid synthesis. There are two ACC forms, alpha and beta, encoded by two different genes.  Acetyl-CoA carboxylase 2 also known as ACC2, ACCβ is believed to be instrumental in controlling mitochondrial fatty acid oxidation, as malonyl-CoA inhibits carnitine-palmitoyl-CoA transferase I, thereby regulating the uptake and oxidation of fatty acids in mitochondria. Notably, ACCβ structure includes a catalytic core that is homologous to ACCα, with the addition of a unique peptide of approximately 150 amino acids at the N terminus, which may contribute to its specific regulatory functions in fatty acid metabolism.