Anti-P89 antibodies are protein reagents that detect specific antigens. The P89 antigen is another term for the human protein inner membrane mitochondrial protein, encoded by the IMMT gene. The protein is a known 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. Canonically, it has an amino acid length of 758 residues and a mass of 83.7 kilodaltons. Its subcellular localization is in the mitochondria and it is widely expressed in many tissue types. The P89 protein is a member of the MICOS complex subunit Mic60 protein family.