Cytidine monophosphate, also known as 5'-cytidylic acid and abbreviated CMP, is a nucleotide. It is an ester of phosphoric acid with the nucleoside cytidine. CMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase cytosine. Cytidine monophosphate (CMP) is derived from cytidine triphosphate (CTP) with subsequent loss of two phosphates. The synthesis of the pyrimidines CTP and UTP occurs in the cytoplasm and starts with the formation of carbamoyl phosphate from glutamine and CO2. Next, aspartate undergoes a condensation reaction with carbamoyl-phosphate to form orotic acid. In a subsequent cyclization reaction, the enzyme Aspartate carbamoyltransferase forms N-carbamoyl-aspartate which is converted into dihydroorotic acid by Dihydroorotase. The latter is converted to orotate by Dihydroorotate oxidase. Orotate is covalently linked with a phosphorylated ribosyl unit with Orotate phosphoribosyltransferase (aka "PRPP transferase") catalyzing reaction, yielding orotidine monophosphate (OMP). Orotidine-5-phosphate is decarboxylated by Orotidine-5'-phosphate decarboxylase to form uridine monophosphate (UMP). UMP is phosphorylated by two kinases to uridine triphosphate (UTP) via two sequential reactions with ATP. CTP is subsequently formed by amination of UTP by the catalytic activity of CTP synthetase. Cytosine monophosphate (CMP) and uridine monophosphate (UMP) have been prescribed for the treatment of neuromuscular affections in humans. Patients treated with CMP/UMP recover from altered neurological functions. Additionally, the administration of CMP/UMP appears to favour the entry of glucose in the muscle and CMP/UMP may be important in maintaining the level of hepatic glycogen constant during exercise. [PMID:18663991].
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