UMP SYNTHASE

Uridine esterified by phosphoric acid on one or more sugar hydroxyl groups; UMP is typically uridine 5'-monophosphate; 2' and 3' derivatives also occur; precursor for the biosynthesis of another pyrimidine nucleotides. Synonym: UMP synthase, uridine 5'-monophosphate. Uridylic acid synthase, a bifunctional enzyme that contains the activities of both orotate phosphoribosyltransferase and orotidine-5'-monophosphate decarboxylase; catalyses a key step in pyrimidine biosynthesis; a deficiency of this enzyme leads to orotic aciduria.