Rsm22-1 is involved in mitochondrion-encoded protein synthesis. Cox11-1 exerts its effect at some terminal stage of cytochrome c oxidase synthesis, probably by being involved in the insertion of the copper B into subunit I. Specific enzymatic cleavages in vivo by mitochondrial processing peptidase (MPP) yield mature proteins including rsm22-1 and cox11-1. In the N-terminal section; belongs to the methyltransferase superfamily. Rsm22 family. In the C-terminal section; belongs to the COX11/CtaG family.