This domain superfamily is found in carbamoyl dehydratase HypE, which is involved in the maturation of NifE hydrogenase; AIR synthase (PurM) and FGAM synthase (PurL), which are involved in de novo purine biosynthesis; and selenide, water dikinase, an enzyme which synthesizes selenophosphate from selenide and ATP.In PurM this domain, which has an alpha-beta-type fold, is found at the C terminus of the protein.