Component of the mitochondrial respiratory complex IV (CIV, also named cytochrome c oxidase complex), the last enzyme in the mitochondrial electron transport chain which drives oxidative phosphorylation (By similarity). The CIV complex is the component of the respiratory chain that catalyzes the reduction of oxygen to water (By similarity). Acts as an assembly factor that specifically drives the homodimerization of CIV complexes, mediating the formation of mitochondrial respiratory supercomplexes (respirasomes) containing two CIV: supercomplxes with two molecules of CIV show improved activity (By similarity). Despite being highly expressed in brown adipose tissue, not required for thermogenesis (By similarity). {ECO:0000250|UniProtKB:P10174, ECO:0000250|UniProtKB:P56392, ECO:0000250|UniProtKB:Q08CE7}. This is the function of Ensembl gene identifier ENSG00000161281 (COX7A1, cytochrome c oxidase subunit 7A1).