Catabolism and synthesis of leucine, isoleucine and valine are finely balanced, allowing the body to make the most of dietary input but removing excesses to prevent toxic build-up of their corresponding keto-acids. This is the butyryl-CoA dehydrogenase, subunit A domain 3, a largely alpha-helical bundle of the enzyme BCDHK. This enzyme is the regulator of the dehydrogenase complex that breaks branched-chain amino-acids down, by phosphorylating and thereby inactivating it when synthesis is required. The domain is associated with family HATPase_c pfam02518 which is towards the C-terminal.
Jiyao W et al.(2023). "The conserved domain database in 2023.",