Mitochondrial inner membrane protein is a protein that in humans is encoded by the IMMT gene. IMMT encodes an inner mitochondrial membrane (IMM) protein in the nucleus. It is posttranslational transported to the IMM. Mic60/Mitofilin (encoded by the IMMT gene) is a core subunit of the MICOS-complex, directly located next to cristae junctions (CJ). Human Mic60 exists in two isoforms of different size, anchored to the IMM via its N-terminus, while most of the protein is located to the inner mitochondrial space (IMS). Mic60 is evolutionary one of the oldest MICOS subunits as homologous were found in anaerobic prokaryotes. It is mainly present in two isoforms (ca. 88 and 90 kDa). In the brain, four isoforms are known, which differ in their isoelectric point due to different post-translational modifications. The amino terminus of Mic60 is anchored in the IM, while most of the protein is extended to the IMS. C-terminal Mic60 has a conserved mitofilin domain which is crucial for building the MICOS-complex. A central coiled-coil domain is required to enable protein-protein interactions.