This is the BC-CT interaction domain (BT) which is between the BC (biotin carboxylase, which catalyses the MgATP-dependent carboxylation of N1' atom of biotin) and BCCP (biotin carboxyl carrier protein) domains of Acetyl-CoA carboxylase. This domain helps to mediate interactions between the BC and CT (carboxyltransferase) domains [1-3].

1: Crystal structure of the 500-kDa yeast acetyl-CoA carboxylase holoenzyme dimer. Wei J, Tong L; Nature. 2015;526:723-727. PMID:26458104

2: The dynamic organization of fungal acetyl-CoA carboxylase. Hunkeler M, Stuttfeld E, Hagmann A, Imseng S, Maier T; Nat Commun. 2016;7:11196. PMID:27073141

3: Structural basis for regulation of human acetyl-CoA carboxylase. Hunkeler M, Hagmann A, Stuttfeld E, Chami M, Guri Y, Stahlberg H, Maier T; Nature. 2018;558:470-474. PMID:29899443