COA5 (Cytochrome C Oxidase Assembly Factor 5) is a Protein Coding gene. The COA5 gene, located on 2q11.2, is conserved in chimpanzee, Rhesus monkey, dog, cow, mouse, rat, chicken, zebrafish, and frog. The COA5 gene produces an 8 kDa protein composed of 73 amino acids. The structure of the protein contains the twin CX9C motif of yeast Pet191, which is conserved in the 74-amino acid deduced human protein. This gene encodes an ortholog of yeast Pet191, which in yeast is a subunit of a large oligomeric complex associated with the mitochondrial inner membrane, and is required for the assembly of the cytochrome c oxidase complex. Mutations in this gene are associated with mitochondrial complex IV deficiency, a disorder of the mitochondrial respiratory chain with heterogeneous clinical manifestations, ranging from isolated myopathy to a severe disease affecting several tissues and organs.