Plays a role in the early steps of cytochrome c oxidase subunit II (MT-CO2/COX2) maturation and is required for the stabilization of COX20 and the newly synthesized MT-CO2/COX2 protein. Found in a complex with COX20, COA6, MT-CO2/COX2, COX18, SCO1 and SCO2. Interacts with COX20. Interacts with COX1, MT-CO2/COX2, SCO1 and SCO2 in a COX20-dependent manner. Belongs to the TMEM177 family.