Lipid-binding START domain of mammalian STARD15 and related proteins
This subgroup includes the steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) domains of STARD15/ACOT12 (also known as cytoplasmic acetyl-CoA hydrolase/CACH, THEAL, and MGC105114) and related domains. It belongs to the START domain family, and in turn to the SRPBCC (START/RHO_alpha_C/PITP/Bet_v1/CoxG/CalC) domain superfamily of proteins that bind hydrophobic ligands. SRPBCC domains have a deep hydrophobic ligand-binding pocket. STARD15/ACOT12 is a type II acetyl-CoA thioesterase; it catalyzes the hydrolysis of acyl-CoAs to free fatty acid and CoASH. Rat CACH hydrolyzes acetyl-CoA to acetate and CoA. In addition to having a START domain, most proteins in this subgroup have two tandem copies of the hotdog domain. Human STARD15/ACOT12 may have roles in cholesterol metabolism and in beta-oxidation.