Deoxycytidine kinase is reversibly phosphorylated in normal human lymphocytes.
The activity of deoxycytidine kinase (dCK) has been shown to be enhanced upon genotoxic stress in human lymphocytes, and reversible phosphorylation of the enzyme has been implicated in the activation process. Here, we provide compelling evidence that dCK is a cytosolic phosphoprotein. Two-dimensional gel electrophoresis revealed that dCK has several differentially charged isoforms in cells. One-third of total cellular dCK was bound to a phosphoprotein-binding column irrespective of its activity levels, indicating that other mechanisms rather than phosphorylation alone might also be involved in the stimulation of enzyme activity. We excluded the possibility that activated dCK is translocated to the nucleus, but identified a dCK isoform of low abundance with a higher molecular weight in the nuclear fractions.
Keszler
G
G
Institute of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary. keszler@puskin.sote.hu
Spasokoukotskaja
T
T
Sasvári-Székely
M
M
Eriksson
S
S
Staub
M
M
D016590:Aphidicolin / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D003842:Deoxycytidine Kinase / Q000737:chemistry* / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D008214:Lymphocytes / Q000201:enzymology*; D014066:Palatine Tonsil / Q000166:cytology; D010750:Phosphoproteins / Q000737:chemistry; D010766:Phosphorylation; D020033:Protein Isoforms; D013347:Subcellular Fractions / Q000378:metabolism
D010750:Phosphoproteins; D020033:Protein Isoforms; D016590:Aphidicolin; D003842:Deoxycytidine Kinase