Component of the acetyl coenzyme A carboxylase (ACC) complex. Biotin carboxylase (BC) catalyzes the carboxylation of biotin on its carrier protein (BCCP) and then the CO(2) group is transferred by the transcarboxylase to acetyl-CoA to form malonyl-CoA. acetyl-CoA + N(6)-carboxybiotinyl-L-lysyl-[protein] = malonyl-CoA + N(6)-biotinyl-L-lysyl-[protein] Binds 1 zinc ion per subunit. Inhibited by pyrrolidine dione antibiotics moiramide B (CPD1) and CPD2. Lipid metabolism; malonyl-CoA biosynthesis; malonyl-CoA from acetyl-CoA: step 1/1. Acetyl-CoA carboxylase is a heterohexamer composed of biotin carboxyl carrier protein (AccB), biotin carboxylase (AccC) and two subunits each of ACCase subunit alpha (AccA) and ACCase subunit beta (AccD). Belongs to the AccD/PCCB family. Truncated N-terminus.