Cytidine 5γ-triphosphate (CTP) is used to synthesize RNA by various RNA polymerases. Cytidine 5γ-triphosphate (CTP) is a substrate for CMP-neuNAc synthetase(s) which produce CMP-neuNAc used in sialylation reactions. As a substrate of CTP:phosphocholine cytidylyltransferase(s) (CT), CTP supports the formation of phosphatidylcholine via the formation of CDP-choline.