Anti-MT-CO1 antibodies are used in the immunodetection of the protein mitochondrially encoded cytochrome c oxidase I. In humans, the canonical protein has a reported length of 513 amino acid residues and a mass of 57 kDa. Its subcellular localization is in the mitochondria. It is notably widely expressed in many tissue types. A member of the Heme-copper respiratory oxidase protein family, MT-CO1 is a known component of the cytochrome c oxidase, the last enzyme in the mitochondrial electron transport chain which drives oxidative phosphorylation. The MT-CO1 gene has been associated with the disease, Leber hereditary optic neuropathy. Synonyms for this target antigen include MTCO1, cytochrome c oxidase subunit I, and COI.