This small family of proteins is currently restricted Methanosarcina species. Members of this family are about 200 residues in length, except for Swiss:Q8TMK1 that has two copies of this region. Although the function of this region is unknown the pattern of conservation suggests that this may be an enzyme, including multiple conserved aspartate and glutamate residues (Bateman A. pers. obs.). The most conserved motif in these proteins is NEL/MEXNE/D, where X can be any amino acid, which is found at the C-terminus of these proteins.