| First Author | Hüttemann M | Year | 2003 |
| Journal | Gene | Volume | 312 |
| Pages | 95-102 | PubMed ID | 12909344 |
| Mgi Jnum | J:85326 | Mgi Id | MGI:2674089 |
| Doi | 10.1016/s0378-1119(03)00604-8 | Citation | Huttemann M, et al. (2003) A third isoform of cytochrome c oxidase subunit VIII is present in mammals. Gene 312:95-102 |
| abstractText | The terminal enzyme of the mitochondrial respiratory chain, cytochrome c oxidase (COX), contains three mitochondrial and ten nuclear encoded subunits in mammals. Three of the nuclear subunits (VIa, VIIa, and VIII) have muscle and non-muscle-specific isoforms, subunit IV contains a lung-specific isoform, and subunit VIb contains a testes-specific isoform. For subunit VIII, the smallest nuclear encoded COX polypeptide, we have now found a third gene (COX 8-3), which has been identified in human, lemur, rat, and mouse, suggesting that it is present in a broad range of Eutherian mammals. Sequence similarity and gene structure support the homology of COX8-3 to the other subunit VIII isoforms, indicating that all three are the product of gene duplications. COX VIII-3 protein is mitochondrially-targeted, as shown by a fluorescent COX VIII3/DsRed fusion protein. Both the mitochondrial targeting and its sequence conservation suggest that COXVIII-3 functions as part of the COX holoenzyme and could have a tissue-specific role, as is the case for the other two isoforms. Questions remain about where COX8-3 is predominantly expressed. However, detection of full-length cDNAs, lower levels of sequence divergence at the first and second codon positions compared to the third, and a conserved gene structure indicate that COX VIII-3 is an expressed gene whose origin dates to at least 91 million years ago. |
