ACACB
Domain
Consists of an N-terminal biotin carboxylation/carboxylase (BC) domain that catalyzes the ATP-dependent transient carboxylation of the biotin covalently attached to the central biotinyl-binding/biotin carboxyl carrier (BCC) domain (Probable). The C-terminal carboxyl transferase (CT) domain catalyzes the transfer of the carboxyl group from carboxylated biotin to acetyl-CoA to produce malonyl-CoA (Probable).
Function
Mitochondrial enzyme that catalyzes the carboxylation of acetyl-CoA to malonyl-CoA and plays a central role in fatty acid metabolism (PubMed:16854592, PubMed:19236960, PubMed:19900410, PubMed:20457939, PubMed:20952656, PubMed:26976583). Catalyzes a 2 steps reaction starting with the ATP-dependent carboxylation of the biotin carried by the biotin carboxyl carrier (BCC) domain followed by the transfer of the carboxyl group from carboxylated biotin to acetyl-CoA (PubMed:19236960, PubMed:20457939, PubMed:20952656, PubMed:26976583). Through the production of malonyl-CoA that allosterically inhibits carnitine palmitoyltransferase 1 at the mitochondria, negatively regulates fatty acid oxidation (By similarity). Together with its cytosolic isozyme ACACA, which is involved in de novo fatty acid biosynthesis, promotes lipid storage (By similarity).
Pathway
Lipid metabolism; malonyl-CoA biosynthesis; malonyl-CoA from acetyl-CoA: step 1/1.
Post-translational modifications
The biotin cofactor is covalently attached to the central biotinyl-binding domain and is required for the catalytic activity.
Phosphorylation at Ser-222 by AMPK inactivates the enzyme (PubMed:12488245). Required for the maintenance of skeletal muscle lipid and glucose homeostasis (By similarity).
Tissue Specificity
Widely expressed with highest levels in heart, skeletal muscle, liver, adipose tissue, mammary gland, adrenal gland and colon (PubMed:9099716). Isoform 3 is expressed in skeletal muscle, adipose tissue and liver (at protein level) (PubMed:19190759). Isoform 3 is detected at high levels in adipose tissue with lower levels in heart, liver, skeletal muscle and testis (PubMed:19190759).
Cellular localization
- Mitochondrion
Alternative names
ACC2, ACCB, ACACB, Acetyl-CoA carboxylase 2, ACC-beta