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. Plays an important role in the regulation of copper homeostasis by controlling the abundance and cell membrane localization of copper transporter CTR1. Homodimer. Interacts with COA6. Found in a complex with TMEM177, COX20, COA6, MT-CO2/COX2, COX18 and SCO2. Interacts with TMEM177 in a COX20-dependent manner. Interacts with COX20 in a MT-CO2/COX2- and COX18-dependent manner. Interacts with COX16. Belongs to the SCO1/2 family.