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)

Reuber (H35) hepatoma cells were grown in medium containing 10(-5)M bromodeoxyuridine (BrdU), which was incorporated into their DNA. Cell growth rate was unaffected by BrdU for the first two generations, after which it was reduced by about 50%. The effect of BrdU incorporation on the activities of several enzymes with rapid turnover rates was examined to test the hypothesis that the synthesis of such enzymes will be preferentially inhibited by BrdU. Tyrosine amino-transferase (TAT) activity decreased by 70% within two generations whereas thymidine kinase activity remained at control values. PEP carboxykinase activity was unchanged during the first generation in BrdU-containing medium but, during the second, its activity increased by at least 30%. Ornithine decarboxylase levels decreased by about 50% only after two generations in the presence of BrdU. There appeared to be no simple relationship between turnover rates and the effect of BrdU on enzyme activity. Incorporation of BrdU was found to inhibit the induction of both TAT and PEP carboxykinase by dexamethasone and to enhance the inhibition of cell growth by this steroid. These results are discussed with respect to possible mechanisms of gene expression and development in both normal and neoplastic cells.
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PMID:The diverse effects of 5'-bromodeoxyuridine on enzyme activities in cultured H35 hepatoma cells. 1 36

Transcription of the gene for cytosolic Phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) (PEPCK) from rat liver is increased by cAMP and glucocorticoids and decreased by insulin. A PEPCK-thymidine kinase (TK) chimeric gene was transfected into FTO-2B rat hepatoma cells, which were TK-deficient. Previous studies showed that a cAMP regulatory element is located at the 5' end of the PEPCK gene. In this report, we demonstrate that the 5' end of the gene also contains a glucocorticoid regulatory element, but not one for insulin. Regions of the PEPCK gene that contain these regulatory elements were attached to the Herpes simplex virus TK structural gene containing its own promoter. The hormone regulatory elements within the 5' flanking region of the PEPCK gene conferred cAMP and glucocorticoid responsiveness on the TK gene after transfection into FTO-2B cells. Like viral enhancer elements, these regulatory elements functioned properly when placed in either orientation at various positions 5' or 3' to TK. The presence of the SV40 enhancer element upstream from the PEPCK-TK gene had little effect on the basal level of expression or hormonal regulation of the chimeric gene.
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PMID:Characterization of the phosphoenolpyruvate carboxykinase (GTP) promoter-regulatory region. I. Multiple hormone regulatory elements and the effects of enhancers. 301 2

Cytoplasmic fractions from species of the Mollicutes genera Entomoplasma, Mesoplasma, Mycoplasma, and Acholeplasma were assayed for NADH oxidase (NADH ox), ATP- and PPi-dependent phosphofructokinase (PFK), ATP- and PPi-dependent deoxyguanosine kinase (dGUOK), thymidine kinase (TK), TMP kinase (TMPK), glucose-6-phosphate dehydrogenase (G6Pde), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), phosphoenolpyruvate carboxylase, hypoxanthine-guanine phosphoribosyl transferase, dUTPase, and uracil-DNA glycosylase (UNG) activities. Membrane fractions were also examined for NADH ox activity. These activities were used as indicators of the presence and relative activities of major Mollicutes metabolic and DNA repair pathways. This was the first study to determine the presence of these enzymes in members of the genera Entomoplasma and Mesoplasma. Using the data obtained, we constructed a preliminary scheme for distinguishing genera of the class Mollicutes on the basis of the results of signature functional enzyme assays. This scheme includes phylogenetic relationships deduced from rRNA analyses, but is more informative with respect to metabolic potential. The criteria used include the presence of PPi-dependent PFK, urease, dUTPase, and dGUOK activities. Entomoplasma ellychniae ELCN-1T (T = type strain), Entomoplasma melaleucae M-1T, Mesoplasma seiffertii F7T, Mesoplasma entomophilum TACT, Mesoplasma florum L1T, Mycoplasma fermentans PG18T, and Acholeplasma multilocale PN525T were similar in most respects. NADH ox activity was localized in the cytoplasm of these organisms. These strains had ATP-dependent PFK, MDH, LDH, ATP- and PPi-dependent dGUOK, and UNG activities, but not dUTPase or G6Pde activities. In contrast, Acholeplasma equifetale C112T, Acholeplasma oculi 19LT, Acholeplasma hippikon C1T, Acholeplasma modicum PG49T, and Acholeplasma morum 72-043T had membrane-localized NADH ox activity, PPi-dependent PFK, G6Pde, and dUTPase activities, and significantly lower MDH and LDH activities and exhibited a faster rate with PPi than with ATP in the dGUOK reaction. All of the members of the Mollicutes tested had hypoxanthine-guanine phosphoribosyl transferase, phosphoenolpyruvate carboxylase, and (except for Mesoplasma entomophilum TAC(T)) UNG activities. All of the Acholeplasma strains except Acholeplasma multilocale PN525T had TK, TMPK, and UNG activities. Mesoplasma entomophilum TAC(T) was distinguished by having no detectable dUTPase, UNG, TK, and TMPK activities, indicating that there is a severe restriction in or an absence of a synthetic route to dTTP. Our data also suggest that A. multilocale PN525T is a member of an unrecognized metabolic subgroup of the genus Acholeplasma or is not an Acholeplasma strain.
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PMID:Comparative metabolism of Mesoplasma, Entomoplasma, Mycoplasma, and Acholeplasma. 886 14