High Quality Content by WIKIPEDIA articles! Protein SCO1 homolog, mitochondrial is a protein that in humans is encoded by the SCO1 gene. Mutations in both SCO1 and SCO2 are associated with distinct clinical phenotypes as well as tissue-specific cytochrome c oxidase deficiency. SCO1 localizes predominantly to blood vessels, whereas SCO2 is barely detectable. Expression of SCO1 is also much higher than that of SCO2 in muscle tissue, while SCO2 is expressed at higher levels in liver tissue than SCO1.