Required for the insertion of integral membrane proteins into the mitochondrial inner membrane. Essential for the activity and assembly of cytochrome oxidase. Required for the correct biogenesis of ATP synthase and complex I in mitochondria. Monomer; predominantly monomeric at low salt concentrations. Homooligomer; predominantly homooligomeric at high salt concentrations. Homodimer. Homotetramer. Interacts with MRPL13, MRPL20, MRPL28, MRPL48, MRPL49 and MRPL51. Associates preferentially as a dimer with the large ribosomal subunit 39S of the mitochondrial ribosome. Belongs to the OXA1/ALB3/YidC family. Extended N-terminus.