IUBMB Enzyme Nomenclature


Accepted name: uridine/cytidine kinase

Reaction: (1) ATP + uridine = ADP + UMP
(2) ATP + cytidine = ADP + CMP

Other name(s): UCK (gene name); URK1 (gene name); pyrimidine ribonucleoside kinase; uridine-cytidine kinase; uridine kinase (phosphorylating); uridine phosphokinase; ATP:uridine 5'-phosphotransferase; uridine kinase

Systematic name: ATP:uridine/cytidine 5'-phosphotransferase

Comments: The enzyme, found in prokaryotes and eukaryotes, phosphorylates both uridine and cytidine to their monophosphate forms. The enzyme from Escherichia coli prefers GTP to ATP. The human enzyme also catalyses the phosphorylation of several cytotoxic ribonucleoside analogs. cf. EC, cytidine kinase.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9026-39-5


1. Sköld, O. Uridine kinase from Erlich ascites tumor: purification and properties. J. Biol. Chem. 235 (1960) 3273-3279.

2. Orengo, A. Regulation of enzymic activity by metabolites. I. Uridine-cytidine kinase of Novikoff ascites rat tumor. J. Biol. Chem. 244 (1969) 2204-2209. [PMID: 5782006]

3. Valentin-Hansen, P. Uridine-cytidine kinase from Escherichia coli. Methods Enzymol. 51 (1978) 308-314. [PMID: 211379]

4. Kern, L. The URK1 gene of Saccharomyces cerevisiae encoding uridine kinase. Nucleic Acids Res. 18 (1990) 5279. [PMID: 2169608]

5. Van Rompay, A.R., Norda, A., Linden, K., Johansson, M. and Karlsson, A. Phosphorylation of uridine and cytidine nucleoside analogs by two human uridine-cytidine kinases. Mol. Pharmacol. 59 (2001) 1181-1186. [PMID: 11306702]

6. Ohler, L., Niopek-Witz, S., Mainguet, S.E. and Mohlmann, T. Pyrimidine salvage: physiological functions and interaction with chloroplast biogenesis. Plant Physiol. 180 (2019) 1816-1828. [PMID: 31101721]

[EC created 1965, modified 2020]

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