AAK_UMPK-PyrH-Pf: UMP kinase (UMPK)-Pf, the mostly archaeal uridine monophosphate kinase (uridylate kinase) enzymes that catalyze UMP phosphorylation and play a key role in pyrimidine nucleotide biosynthesis; regulation of this process is via feed-back control and via gene repression of carbamoyl phosphate synthetase (the first enzyme of the pyrimidine biosynthesis pathway). The UMP kinase of Pyrococcus furiosus (Pf) is known to function as a homohexamer, with GTP and UTP being allosteric effectors. Like other related enzymes (carbamate kinase, aspartokinase, and N-acetylglutamate kinase) the E. coli and most bacterial UMPKs have a conserved, N-terminal, lysine residue proposed to function in the catalysis of the phosphoryl group transfer, whereas most archaeal UMPKs (this CD) appear to lack this residue and the Pyrococcus furiosus structure has an additional Mg ion bound to the ATP molecule which is proposed to function as the catalysis instead. Members of this CD belong to the Amino Acid Kinase Superfamily (AAK).