The gene that codes for the isobutyryl-CoA dehydrogenase has not yet been identified in D. melanogaster. In mammals, propanoyl-CoA is converted to succinyl-CoA by the PCCA and PCCB propanoyl-CoA carboxylase complex, methylmalonyl-CoA epimerase MCEE and methylmalonyl-CoA mutase MMUT. Although propanoyl-CoA carboxylase activity has been detected in D. melanogaster, there is no homolog of mammalian PCCA, PBBC, MCEE or MMUT. Some evidence suggests that propanoyl-CoA may be converted to acetate via 3-hydroxypropionate.