Isolation of a cDNA specifying subunit VIIb of human cytochrome c oxidase

Abstract

Human cytochrome c oxidase (COX) is a complex of 13 subunits: three are encoded by mitochondrial DNA and ten by nuclear DNA. We have now isolated a full-length cDNA specifying subunit VIIb, the last remaining uncharacterized nuclear-encoded subunit cDNA of human COX. The cDNA encodes a deduced 80-aa polypeptide, including a 24-amino acid (aa) N-terminal leader sequence and a 56-aa mature polypeptide with 82% identity to mature bovine COX VIIb. Southern blot hybridization of human muscle genomic DNA showed multiple hybridizing bands, implying the presence of a large coxVIIb gene family, including a potential processed pseudogene.