Catalyzes the removal of transit peptides required for the targeting of proteins from the mitochondrial matrix, across the inner membrane, into the inter-membrane space. Known to process the nuclear encoded protein DIABLO. Heterodimer of 2 subunits, IMMPL1 and IMMPL2. Expressed in all tissues tested except adult liver and lung. The disease may be caused by variants affecting the gene represented in this entry. Belongs to the peptidase S26 family. IMP2 subfamily.