This enzyme, part of an acetyl-CoA carboxylase complex, acts on a biotin carboxyl-carrier protein (BCCP) that has been biotinylated by EC
6.3.4.15, biotin---[biotin carboxyl-carrier protein] ligase. In some organisms the enzyme is part of a multi-domain polypeptide that also includes the carrier protein (e.g. mycobacteria). Yet in other organisms (e.g. mammals) this activity is included in a single polypeptide that also catalyses the transfer of the carboxyl group from biotin to acetyl-CoA (see EC
6.4.1.2, acetyl-CoA carboxylase).