InterPro domain: IPR004549

This family represents the biotin carboxylase subunit found usually as a component of acetyl-CoA carboxylase. Acetyl-CoA carboxylase ( 6.4.1.2 ) is a heterohexamer of biotin carboxyl carrier protein, biotin carboxylase ( 6.3.4.14 ), and two subunits of carboxyl transferase in a 2:2 complex. In the first step of long-chain fatty acid synthesis, biotin carboxylase catalyses the carboxylation of the carrier protein and then the transcarboxylase transfers the carboxyl group to form malonyl-coA. Homologous domains are found in eukaryotic forms of acetyl-CoA carboxylase and in a number of other carboxylases (e.g. pyruvate carboxylase). In some systems, the biotin carboxyl carrier protein and this protein (biotin carboxylase) may be shared by different carboxyltransferases. However, this model is not intended to identify the biotin carboxylase domain of propionyl-coA carboxylase. The model should hit the full length of proteins, except for chloroplast transit peptides in plants. If it hits a domain only of a longer protein, there may be a problem with the identification.