Cytidine 5'-triphosphate (CTP) is a pyrimidine nucleoside triphosphate that is involved in a variety of biochemical reactions. It is used in the synthesis of RNA by RNA polymerases. In the formation of phosphatidylcholine (PC), CTP reacts with phosphocholine, via CTP:phosphocholine cytidylyltransferases, to produce CDP-choline and diphosphate. This is the rate-limiting step in PC synthesis and, as a pivotal step in cell proliferation, can be important in cancer. CTP also interacts with N-acylneuraminate, in a reaction mediated by N-acylneuraminate cytidylyltransferase, to generate an intermediate that is required for sialylation, namely CMP-N-acylneuraminic acid.
