Copper metallochaperone essential for the maturation of cytochrome c oxidase subunit II (MT-CO2/COX2). Not required for the synthesis of MT-CO2/COX2 but plays a crucial role in stabilizing MT-CO2/COX2 during its subsequent maturation. Involved in transporting copper to the Cu(A) site on MT-CO2/COX2 (PubMed:15659396, PubMed:16735468, PubMed:17189203, PubMed:19336478, PubMed:15229189). Plays an important role in the regulation of copper homeostasis by controlling the abundance and cell membrane localization of copper transporter CTR1 (By similarity). Homodimer (PubMed:16735468, PubMed:15229189). Interacts with COA6 (PubMed:26160915). Found in a complex with TMEM177, COX20, COA6, MT-CO2/COX2, COX18 and SCO2 (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). Predominantly expressed in tissues characterized by high rates of oxidative phosphorylation (OxPhos), including muscle, heart, and brain. The disease is caused by variants affecting the gene represented in this entry. Belongs to the SCO1/2 family.