Five transmembrane core domain of mitochondrial inner membrane protein Oxa1 and similar proteins
This group is composed mostly of the mitochondrial members of the YidC/Oxa1/Alb3 protein family of insertases, including mitochondrial inner membrane proteins Oxa1, Oxa1-like (Oxa1L), cytochrome c oxidase assembly protein 18 (Cox18, also called Oxa2), and Arabidopsis thaliana mitochondrial ALBINO3-like protein 3 (ALB33). It also includes Arabidopsis thaliana chloroplastic ALBINO3-like protein 2 (ALB32). Members of this group mediate the insertion of both mitochondrion-encoded precursors and nuclear-encoded proteins from the matrix into the mitochondrial inner membrane. Oxa1 and Cox18/Oxa2 are essential for the activity and assembly of cytochrome c oxidase, playing central roles in the translocation and export of the N-terminal and C-terminal parts, respectively, of the COX2 protein into the mitochondrial intermembrane space. ALB32 may be involved in the insertion of integral membrane proteins into the chloroplast thylakoid membranes. YidC/Oxa1/Alb3 family insertases contain a core domain of five transmembrane (5TM) segments that is essential to insertase function.