sequence of mitochondrial branched-chain aminotransferase BCAT2_MOUSE BCAT(m) Bcat-2 Bcat2 Bcatm Branched-chain-amino-acid aminotransferase, mitochondrial EC 2.6.1.42 Eca40 IMR:0703473 UniProt:O35855 branched chain aminotransferase 2, mitochondrial molecule_role