Orotidine 5'-monophosphate
Encyclopedia
Orotidine 5'-monophosphate (OMP), also known as orotidylic acid, is a pyrimidine
Pyrimidine
Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring...

 nucleotide
Nucleotide
Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...

 which is the last intermediate in the biosynthesis of uridine monophosphate
Uridine monophosphate
Uridine monophosphate, also known as 5'-uridylic acid and abbreviated UMP, is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside uridine...

. OMP is formed from orotate and phosphoribosyl pyrophosphate
Phosphoribosyl pyrophosphate
Phosphoribosyl pyrophosphate is a pentosephosphate.It is formed from ribose 5-phosphate by the enzyme ribose-phosphate diphosphokinase.It plays a role in transferring phospho-ribose groups in several reactions:...

 by the enzyme Orotate phosphoribosyltransferase
Orotate phosphoribosyltransferase
Orotate phosphoribosyltransferase is an enzyme involved in pyrimidine biosynthesis. It catalyzes the formation of orotidine 5'-monophosphate from orotate and phosphoribosyl pyrophosphate...



In humans, the enzyme UMP synthase converts OMP into uridine 5'- monophosphate. If UMP synthase is defective, orotic aciduria
Orotic aciduria
-Signs and symptoms:In addition to the characteristic excessive orotic acid in the urine, patients typically have megaloblastic anemia which cannot be cured by administration of vitamin B12 or folic acid....

can result.
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