The branched-chain alpha-keto dehydrogenase complex catalyzes the overall conversion of alpha-keto acids to acyl-CoA and CO(2) (By similarity). It contains multiple copies of three enzymatic components: branched-chain alpha-keto acid decarboxylase (E1), lipoamide acyltransferase (E2) and lipoamide dehydrogenase (E3) (By similarity). Within this complex, the catalytic function of this enzyme is to accept, and to transfer to coenzyme A, acyl groups that are generated by the branched-chain alpha-keto acid decarboxylase component (By similarity). Required for the catabolism of branched-chain amino acids and the subsequent synthesis of monomethyl branched-chain fatty acids, which are important for regulating postembryonic growth (PubMed:26683372). (R)-N(6)-dihydrolipoyl-L-lysyl-[protein] + 2-methylpropanoyl-CoA = (R)-N(6)-(S(8)-2-methylpropanoyldihydrolipoyl)-L-lysyl-[protein] + CoA Binds 1 lipoyl cofactor covalently. Localizes to puncta within the cytosol which is consistent with its expected location in mitochondria. Ubiquitously expressed. RNAi-mediated knockdown results in reduced monomethyl branched-chain fatty acid generation and also results in larval arrest in the subsequent generation. Belongs to the 2-oxoacid dehydrogenase family.