Component of the MICOS complex, a large protein complex of the mitochondrial inner membrane that plays crucial roles in the maintenance of crista junctions, inner membrane architecture, and formation of contact sites to the outer membrane. Component of the mitochondrial contact site and cristae organizing system (MICOS) complex (also known as MINOS or MitOS complex). Belongs to the apolipoprotein O/MICOS complex subunit Mic27 family.