Center for Bioinformatics
Oxidoreductases | Transferases | Hydrolases | Lyases | Isomerases | Ligases

Basic Information

Enzyme Number

Official Name

uridine kinase

Name from literature

Uridine-cytidine nucleoside kinase

Pathway from literature

pyrimidine-nucleotide salvage pathway

Pathway from KEGG

Xenobiotics Biodegradation and Metabolism; Drug metabolism - other enzymes; map00983

Nucleotide Metabolism; Pyrimidine metabolism; map00240


Human (9606)

Genome localization

20q13.33[54963 ], 9q34.13[83549 ], 1q23[7371 ],


Cytidine can act as acceptor; GTP and ITP can act as donors.

Rate-limiting Description

"Further, comparisons of the Km values of isolated uridine kinases with those for cellular uptake of pyrimidine nucleosides and their rate of intracellular phosphorylation suggest that nucleoside-transport systems play a rate-limiting role in nucleoside analogue activation and consequently that it is impossible to estimate the Km of uridine kinase in the intact cell." (195585)

"The activity of uridine kinase (ATP: uridine 5'-phosphotransferase; EC, the rate-limiting enzyme of the UMP salvage pathway, was measured in human ovaries and ovarian carcinomas, in a spectrum of six rat hepatomas of different growth rates and in eleven normal rat tissues of high and low cell renewal rates." (9923963)

"Uridine-cytidine nucleoside kinase 2 (UCK2) is the rate-limiting enzyme in the pyrimidine-nucleotide salvage pathway." (15735337)

Regulatory Information

Regulatory type



"Free UCK takes an alpha/beta mononucleotide binding fold and exists as a homotetramer with 222 symmetry. Upon inhibitor binding, one loop region was loosened, causing the UCK tetramer to be distorted." (15130468)


"Global, in vivo, and site-specific phosphorylation dynamics in signaling networks." (17081983#16964243)

signal pathway;

"The differences between EGF and EGF-CNBr cellular processing made it possible to discuss potential ways of uridine-kinase activity regulation during the early period of stimulation of quiescent cell cultures." (3500535)

key enzyme;

"The activity of uridine-cytidine kinase (Urd-Cyd kinase). a key enzyme in the salvage of pyrimidine nucleosides" (7126259#232427)









Gene ontology

Gene ontology

GO:0005783 (C) endoplasmic reticulum [Q9NWZ5 ];
GO:0004849 (F) uridine kinase activity [Q9HA47, Q9NWZ5, Q9BZX2 ];
GO:0005829 (C) cytosol [Q9HA47, Q9BZX2 ];
GO:0005524 (F) ATP binding [Q9HA47, Q9NWZ5, Q9BZX2, Q5JT10 ];
GO:0044419 (P) interspecies interaction between organisms [Q9NWZ5 ];
GO:0016301 (F) kinase activity [Q5JT10 ];
GO:0005634 (C) nucleus [Q9NWZ5 ];
GO:0016773 (F) phosphotransferase activity, alcohol group ... [Q9HA47, Q9NWZ5, Q9BZX2, Q5JT10 ];
GO:0008152 (P) metabolic process [Q9HA47, Q9NWZ5, Q9BZX2, Q5JT10 ];

Tissue expression

Tissue From HPRD

Small intestine [18256 ];
Kidney [01882, 18256, 15607 ];
Ubiquitous [15607 ];
Heart [01882, 18256, 15607 ];
Lung [01882, 15607 ];
Macrophage [01882 ];
Pancreas [01882, 15607 ];
Skeletal muscle [01882, 18256, 15607 ];
Liver [01882, 18256, 15607 ];
Placenta [01882, 18256, 15607 ];
Blood [01882 ];
Brain [01882, 18256, 15607 ];
Spleen [18256 ];

Tissue specificity

Testis-specific (PubMed:8812458);
found exclusively in the placenta (PubMed:11306702) [Q9BZX2 ];

Ubiquitous [Q9HA47, Q9NWZ5 ];

Subcellular localization


nucleus [Q9NWZ5 ];

cytoplasm [Q9NWZ5 ];



Q5JT10; Q9BZX2; Q9HA47; Q9NWZ5

Entrez Gene

54963; 7371; 83549


18256; 15607; 01882

  Copyright 2009, Center for Bioinformatics 
  Last Modified: 2009-03-24  
  Design by Zhao Min