Involved in the organization of the mitochondrial membranes and the global structure of the mitochondria. Also required for mitochondrial distribution and mobility as well as for the maintenance of mitochondrial DNA nucleoids structures. Interacts with MDM32. Participates in a complex of about 600 kDa. Present with 1200 molecules/cell in log phase SD medium. Belongs to the MDM31/MDM32 family.