Tg. Petrakis et al., Cloning and characterization of mouse deoxyguanosine kinase - Evidence fora cytoplasmic isoform, J BIOL CHEM, 274(35), 1999, pp. 24726-24730
Deoxyguanosine kinase (dGK) is a nuclear gene product that catalyzes the ph
osphorylation of purine deoxyribonucleosides and their analogues. The human
enzyme is located predominantly in the mitochondria, as shown by biochemic
al fractionation studies and in situ localization of the overexpressed reco
mbinant protein. Here we describe the cloning of mouse dGK cDNA and the ide
ntification of a novel amino-terminally truncated isoform that corresponds
to about 14% of the total dGK mRNA population in mouse spleen. In situ fluo
rescence assays suggest that the new isoform cannot translocate into the mi
tochondria and thus may represent a cytoplasmic enzyme. Expression of mouse
dGK mRNA was highly tissue-specific and differed from the tissue distribut
ion observed in humans. Recombinant mouse dGK showed similar specific activ
ity and substrate specificity as compared with the human enzyme. The broad
specificity, restricted tissue distribution, and location of mouse dGK in m
ultiple cellular compartments raise new considerations with respect to the
role of the individual deoxynucleoside kinases in nucleotide metabolism.