Thiolase domain associated with sterol carrier protein (SCP)-x isoform and related proteins; SCP-2 has multiple roles in intracellular lipid circulation and metabolism. The N-terminal presequence in the SCP-x isoform represents a peroxisomal 3-ketacyl-Coa thiolase specific for branched-chain acyl CoAs, which is proteolytically cleaved from the sterol carrier protein.