orotidine-5‵

-phosphate decarboxylase (ODC) orot·i·dine-5‵-phos·phate de·car·box·y·lase (ODC) (ə-rotґĭ-dēn fosґfāt de″kahr-bokґsə-lās) [EC 4.1.1.23] an enzyme of the lyase class that catalyzes the decarboxylation of orotidine 5′-phosphate to form uridine monophosphate in the synthesis of pyrimidine nucleotides. The catalytic sites for this activity and for the orotate phosphoribosyltransferase (OPRT) activity reside on a single protein, called UMP synthase. Deficiency of ODC activity only, an autosomal recessive trait, results in oroticaciduria, type II.