The function of COX17 (cytochrome c oxidase copper chaperone COX17, Ensembl gene identifier ENSG00000138495) is as follows. Copper metallochaperone involved in the assembly of cytochrome c oxidase (respiratory chain complex IV, CIV) (PubMed:15229189, PubMed:19393246, PubMed:31903891, PubMed:35750769). Binds two copper ions and delivers them to metallochaperones SCO1 and SCO2, which co-chaperone the copper ions to the Cu(A) site on the cytochrome c oxidase subunit II (MT-CO2/COX2), and to metallochaperone COX11 which relays the copper to the Cu(B) site on the cytochrome c oxidase subunit I (MT-CO1/COX1) (PubMed:15229189, PubMed:19393246, PubMed:35750769). {ECO:0000269|PubMed:15229189, ECO:0000269|PubMed:19393246, ECO:0000269|PubMed:31903891, ECO:0000269|PubMed:35750769}.