This gene encodes a protein which contains an apolipoprotein O superfamily domain. This domain is found on proteins in circulating lipoprotein complexes. 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. The proein specifically binds to cardiolipin (in vitro) but not to the precursor lipid phosphatidylglycerol. This protein plays a crucial role in crista junction formation and mitochondrial function.