ctaC Cytochrome cba3 subunit 2 COX2_THETH Subunits I and II form the functional core of the enzyme complex. Electrons originating in cytochrome c are transferred via heme a and Cu(A) to the binuclear center formed by heme a3 and Cu(B). Cytochrome c oxidase polypeptide II Cytochrome c ba(3) subunit II 135 Cytochrome c oxidase subunit 2 (Fragment) AYTLATHTAGVIPAGKLERVDPTTVRQEGPWADPAQAVVQTGPNQYTVYVLAFAFGYQPNPIEVPQGAEIVFKITSPDVIHGFHVEGTNINVEVLPGEVSTVRYTFKRPGEYRIICNQYCGLGHQNMFGTIVVKE cbaB