Binds medium- and long-chain acyl-CoA esters with very high affinity and may function as an intracellular carrier of acyl-CoA esters (By similarity). May be involved in energy metabolism in a manner that depends on the substrate used for energy production. Dbi and its metabolites are involved in the regulation of multiple biological processes. Expressed in larval and pupal brains. In adults, expressed in cardia, part of the Malpighian tubules, fat body, and gametes of both sexes. Expressed from the larval stage onwards throughout the adult stage. Belongs to the ACBP family.