Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.21 (thymidine kinase)
 7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mouse fibroblasts resistant to the drug rutamycin were isolated by selectively introducing BrdUrd into the mitochondrial genome of a line of mouse fibroblasts (clone 1 D) lacking a cytoplasmic thymidine kinase enzyme. The ATPase (ATP phosphohydrolase; EC 3.6.1.3) activity of mitochondria isolated from these cells was resistant to rutamycin. The rutamycin-resistant mutants were enucleated with cytochalasin B and fused with mouse A 9 cells resistant to 8-azaguanine and sensitive to rutamycin. Cytoplasmic hybrids, or cybrids, were selected as cells resistant to rutamycin and 8-azaguanine, and appeared at a high frequency. Other fusions between rutamycin-resistant nucleated cells and A 9 produced colonies at a much lower frequency. Finally, fusions between enucleated clone 1 D cells and A 9 cells produced no rutamycin-resistant colonies. These results indicate that rutamycin resistance is a cytoplasmically inherited characteristic in this cell line.
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PMID:Cytoplasmic inheritance of rutamycin resistance in mouse fibroblasts. 14 79

1. Extracts of several plant species contained nucleoside-AMP phosphotransferase activity. The ratio of activity with thymidine to that with uridine as nucleoside substrate was essentially constant, both between species and throughout plant development. Evidence is presented that the total thymidine-AMP phosphotransferase activity of the leaves of Asplenium nidus (bird's-nest fern) and of Helianthus tuberosus (Jerusalem artichoke) increases during maturation. 2. Thymidine-AMP phosphotransferase was purified 22-fold from a very rich source of this activity, extracts of A. nidus. 3. A broad specificity towards both nucleoside and nucleoside 5'-monophosphate substrates is displayed by this preparation, and the evidence suggests that all could be due to a single enzyme. 4. Nucleosides that act as substrates will also inhibit phosphotransfer to other nucleosides, with Ki values close to the corresponding Km values found when utilized as substrates. 5. Ca2+-activated ATP phosphohydrolase was separated from the phosphotransferase by differential complexing to Blue Dextran in the presence of urea, whereas an AMP phosphohydrolase activity was closely associated with thymidine-AMP phosphotransferase through all separation techniques used. 6. Metal ions did not activate either of the latter two activities, and 1,10-phenanthroline was found to inhibit the phosphotransferase. 7. Km values for AMP for the respective activities were 0.11 mM (thymidine phosphotransferase) and 0.20 mM (AMP phosphohydrolase) and for thymidine (phosphotransferase only) 0.88 mM. 8. 3':5'-Cyclic AMP was found to inhibit both phosphotransferase and AMP phosphohydrolase activities, with Ki values of 0.056 mM and 0.15 mM respectively. It is suggested that this inhibitor would be of value in revealing the existence of thymidine kinase in plant extracts with high thymidine phosphotransferase activity.
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PMID:Thymidine phosphotransferase and nucleotide phosphohydrolase of the fern Asplenium nidus. General properties and inhibition by adenosine 3':5'-cyclic monophosphate. 18 31

The activities of TdR kinase2 (ATP: thymidine 5'-phosphotransferase, EC 2.7.1.21), AdR kinase (ATP: deoxyadenosine 5'-phosphotransferase, EC 2.7.1.76), GdR kinase (ATP: deoxyguanosine 5'-phosphotransferase, without EC number), ATP (Mg2+)-ase (ATP phosphohydrolase, EC 3.6.1.3), nucleoside diphosphatase (nucleoside diphosphate phosphohydrolase, EC 3.6.1.6), nucleoside phosphotransferase (AMP: deoxynucleoside phosphotransferase, EC 2.7.1.77) and ribonucleotide 5'-diphosphate reductase (EC 1.17.4.1) were assayed in mitochondria of normal and regenerating rat liver. The activities of deoxynucleoside kinases are regulated: (a) by feedback inhibition of TdR kinase with dTTP and dCTP, and GdR kinase with dGTP; (b) GdR and AdR kinases by AdR and GdR inhibition, respectively; (c) by stimulation of GdR kinase with dTDP, dTTP and dATP. The stimulatory effects are correlated with changes of ATP (Mg2+)-ase and NDP-ase activities in regenerating liver mitochondria.
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PMID:Regulation of deoxynucleoside kinase activities in rat liver mitochondria. 612 3