This family of proteins are mitochondrial 18KDa proteins that are often misannotated as carbonic anhydrases. It was shown that knockdown of MTP18 protein results in a cytochrome c release from mitochondria and consequently leads to apoptosis [1]. Overexpression studies suggest that MTP18 is required for mitochondrial fission [2].

1: Knockdown of MTP18, a novel phosphatidylinositol 3-kinase-dependent protein, affects mitochondrial morphology and induces apoptosis. Tondera D, Santel A, Schwarzer R, Dames S, Giese K, Klippel A, Kaufmann J; J Biol Chem. 2004;279:31544-31555. PMID:15155745

2: The mitochondrial protein MTP18 contributes to mitochondrial fission in mammalian cells. Tondera D, Czauderna F, Paulick K, Schwarzer R, Kaufmann J, Santel A; J Cell Sci. 2005;118:3049-3059. PMID:15985469