ctaC ctaB coxII COX2_RHOSH Oxidase aa(3) subunit 2 303 Cytochrome c oxidase subunit 2 MRHSTTLTGCATGAAGLLAATAAAAQQQSLEIIGRPQPGGTGFQPSASPVATQIHWLDGFILVIIAAITIFVTLLILYAVWRFHEKRNKVPARFTHNSPLEIAWTIVPIVILVAIGAFSLPVLFNQQEIPEADVTVKVTGYQWYWGYEYPDEEISFESYMIGSPATGGDNRMSPEVEQQLIEAGYSRDEFLLATDTAMVVPVNKTVVVQVTGADVIHSWTVPAFGVKQDAVPGRLAQLWFRAEREGIFFGQCSELCGISHAYMPITVKVVSEEAYAAWLEQARGGTYELSSVLPATPAGVSVE Cytochrome c oxidase polypeptide II Cytochrome aa3 subunit 2 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).