Branched-chain ?-keto acid dehydrogenase E1 component ? chain（BCKDHA) is a member of the BCKDHA family. The BCKD（branched-chain alpha-keto acid dehydrogenase) complex is an inner mitochondrial enzyme complex which catalyzes the second major step in the catabolism of the branched-chain amino acids leucine， isoleucine， and valine. This complex consists of 3 catalytic components: a heterotetrameric（alpha2-beta2) branched-chain alpha-keto acid decarboxylase（E1)， a dihydrolipoyl transacylase（E2)， and a dihydrolipoamide dehydrogenase（E3). Mutations in the BCKDHA gene result in maple syrup urine disease， type IA.
