Aminotransferase class-V is an evolutionary conserved protein domain. This domain is found in amino transferases, and other enzymes including cysteine desulphurase EC:4.4.1.-. Aminotransferases share certain mechanistic features with other pyridoxal- phosphate dependent enzymes, such as the covalent binding of the pyridoxal- phosphate group to a lysine residue. On the basis of sequence similarity, these various enzymes can be grouped into subfamilies. This family is called class-V.