Copper metallochaperone essential for the synthesis and maturation of cytochrome c oxidase subunit II (MT-CO2/COX2). Involved in transporting copper to the Cu(A) site on MT-CO2/COX2 (PubMed:15229189, PubMed:17189203). Also acts as a thiol-disulfide oxidoreductase to regulate the redox state of the cysteines in SCO1 during maturation of MT-CO2/COX2 (PubMed:19336478). Homodimer (PubMed:15229189). Interacts with COA6 (PubMed:25959673). Found in a complex with TMEM177, COX20, COA6, MT-CO2/COX2, COX18 and SCO1 (PubMed:29154948). Interacts with TMEM177 in a COX20-dependent manner (PubMed:29154948). Interacts with COX20 in a MT-CO2/COX2- and COX18-dependent manner (PubMed:29154948, PubMed:24403053, PubMed:28330871). Interacts with COX16 (PubMed:29381136). Ubiquitous. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the SCO1/2 family.