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)

A cell line that normally supports the replication of herpes simplex virus types 1 and 2 became resistant to these viruses after transformation by simian adenovirus 7. Kinetic studies of the mechanism of resistance demonstrated that both herpesviruses were able to attach to the transformed cells and express some early genomic functions, as demonstrated by the presence of low levels of viral thymidine kinase. However, isopycnic centrifugation studies of the abortive system failed to detect viral deoxyribonucleic acid synthesis, whereas indirect immunofluorescent studies of viral proteins revealed that less than 10 per cent of the cells contained these viral macromolecules at any given time. Collectively the data suggest that after transformation by simian adenovirus 7 these cells are altered so as to render them resistant or incapable of supporting the growth of herpes simplex virus types 1 and 2. The results further suggest that the block occurs after viral absorption and prior to viral deoxyribonucleic acid synthesis.
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PMID:Adenovirus-transformed cells restrict Herpes simplex virus replication. 16 98

After small bowel resection in the rat, mucosal hyperplasia and an increase in nucleic acid synthesis and cell proliferation occur in remaining small intestine. Male Sprague-Dawley rate underwent resection of 50 cm of proximal or distal intestine or sham operation. One month and 6 months after surgery, aspartate transcarbamylase, dihydroorotase, and uridine kinase were assayed in whole mucosa, and in some instances, in crypt mucosa ffrom the remaining intestinal segment. In control bowel, enzyme activity was significantly greater proximal compared with distal segments. One month after proximal or distal resection, mucosal enzyme activity per cm of gut was greater in the remnant bowel compared with controls. There was no such difference at 6 months. Specific enzyme activity of whole mucosa did not increase after resection because the assay was influenced by the disproportionately large contribution of villous protein. Specific enzyme activity (including thymidine kinase) of isolated crypt mucosa was significantly increased 1 month after distal resection. In addition, [3H]thymidine uptake into DNA of crypt mucosa from proximal remnants was also significantly increased. These results indicate that after small bowel resection, the enzymes of pryimidine biosynthesis increase in remaining bowel and parallel the accelerated rate of cell proliferation.
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PMID:Pyrimidine biosynthetic enzymes in rat intestine after small bowel resection. 16 99

The effect of Rolly No. 11 strain herpes simplex virus infection of HeLa cells in culture on deoxynucleotide metabolism and the level of various enzymes concerned with the biosynthesis of DNA has been investigated. Of 18 enzyme activities studied, thymidine kinase, DNA polymerase and deoxyribonuclease were markedly augmented, a finding in agreement with previous reports. Deoxycytidine kinase, ribonucleotide reductase, thymidylate kinase and deoxycytidylate deaminase activities, in contrast with previous reports, did not increase; the activities of the other enzymes studied, also did not increase. Whereas most of the radioactivity derived from [14-C] thymidine in the acid-soluble fraction of the uninfected cells was present as deoxythymidine triphosphate, that present in the infected cells was primarily in the form of deoxythymidine monophosphate. Thus, in the infected cell deoxythymidylate kinase is a rate-limiting enzyme in the biosynthesis of deoxythymidine triphosphate. A marked increase in the pools of the four naturally occurring deoxynucleoside triphosphates (dTTP, dCTP, dATP, dGTP) was found. The rate of formation of the virus-induced enzymes was determined, as were the various nucleoside triphosphate pools and the other phosphorylated derivatives of thymidine; a maximum was reached for all these csmponents between 6 to 8 h post infection. Although an apparent greater synthesis of DNA occurred in the uninefected cells, when the specific activity of the radioactive deoxythymidine triphosphate was taken into account, there was actually a greater rate of DNA synthesis in the infected cells, with the peak at 8 h post infection.
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PMID:Deoxyribonucleotide metabolism in Herpes simplex virus infected HeLa cells. 16 49

Antiserum prepared against herpes simplex virus type 1 (HSV-1)-infected L cells, i.e., lytic antiserum, was shown by an indirect immunofluorescence test to stain 90 percent of HSV-transformed L or HeLa cells. Immunofluorescence in these cells was always most intense in the perinuclear cytoplasmic region. Similar results were obtained with antiserum prepared against HSV-transformed L cells. These data indicate that HSV-transformed cells (both L and HeLa) express HSV-related antigens. Antiserum prepared against HSV-1-transformed L cells, i.e., transformed-cell antiserum, was found to agglutinate purified HSV type 1 virions but failed to neutralize infectivity. This suggests that HSV-1 structural antigens are expressed in HSV-1-transformed L cells. Immunodiffusion studies showed that at least two HSV-related antigens could be demonstrated with antigens from HSV-1-transformed L cells and transformed-cell antiserum. These two antigens were shown to be present in all clonal lines of HSV-1-transformed cells examined, six L cell lines and one HeLa cell line. Therefore, we conclude that transformation of cells by HSV-1, which is known to be associated with acquisition of viral thymidine kinase, must also be associated with the presence of these two antigens. We performed experiments showing that there are species of HSV-related antibody in HSV-transformed cell antiserum that could not be absorbed out with antigens from HSV-infected L cells. Antibodies present in lytic antiserum were completely removed by antigen preparations from cells lytically infected with HSV-1. Also, lytic antiserum failed to block HSV-related staining of transformed L cells in a direct immunofluorescence test. These results are compatible with one of two notions: either (i) certain genes are expressed during transformation that are not expressed during lytic infection, or (ii) these genes are expressed to a much more reduced extent during lytic infection than in transformed cells.
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PMID:Presence of herpes simplex virus-related antigens in transformed L cells. 16 95

After partial hepatectomy in rats, the following changes in enzymic activities were observed in the remnant liver during the prereplicative period. In the initial period of the prereplicative process, soon after removal of part of the liver, ornithine decarboxylase [EC 4.1.1.17] and IMP dehydrogenase [EC 1.2.1.14] increase. Subsequently, for entry into the S period, thymidine kinase [EC 2.7.1.75] increases simultaneously with increase in the intracellular cyclic AMP level and decrease in its phosphodiesterase [EC 3.1.4.17].
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PMID:Prereplicative enzymic changes in regenerating rat liver. 16 85

Twelve temperature-sensitive (ts) mutants of herpes simplex virus type 1 (HSV-1), representing seven complementation groups, were isolated subsequent to 5-bromodeoxyuridine mutagenesis. These mutants were identified by their inability to replicate in a line of monkey (CV-1) cells at 39 C. Seven of these mutants, representing six complementation groups, induced thymidine kinase (tk) and transformed Ltk- cells, a line of mouse L cells lacking tk, to a tk+ phenotype at both the permissive (34 C) and nonpermissive (39 C) temperatures. Thus, the defective cistrons in these six complementation groups, although necessary for lysis, have no essential function in this transformation system. Transformation by these 12 mutants was dependent on prior UV irradiation. Infection of cells with unirradiated virus under conditions which did not permit virus replication was not sufficient to allow cell transformation. Five mutants, representing two complementation groups, were tk- and were incapable of causing the tk--to-tk+ transformation at either 34 C of 39 C. The tk defects in these mutants are probably unrelated to the ts defects, since one of these complementation groups contains a tk+ member. Therefore, transformation of Ltk- cells to a tk+ phenotype by HSV-1 requires an active viral tk gene. One complementation group was represented by a single tk- member. The role of this cistron in transformation remains undetermined since the primary block to transformation is presumed to be the tk- phenotype. Mutants representing the seven complementation groups were unable to replicate at 39 C in two lines of HSV-1-transformed cells, indicating that the activities of resident wild-type copies of the defective cistrons, if present, could not be detected by complementation.
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PMID:Temperature-sensitive mutants of herpes simplex virus type 1 defective in lysis but not in transformation. 16 2

A somatic hybrid of ASL-1 leukemia cells [H-2a, thymus leukemia (TL)1,2,3, Thy-1b] and LM(TK)-cells [H-2-k, TL(-), Thy-1 (-), thymidine kinase deficient] was formed with the aid of inactivated Sendai virus. The selection of hybrid cell clones was facilitated by the inability of ASL-1 cells to grow in vitro and of LM(TK)-cells to survive in hypoxanthine/amethopterin/thymidine medium. The H-2 antigens of both parental cells were formed in approximately equivalent amounts by the hybrid cells, and they possessed a hybrid karyotype. As determined by five independent experimental procedures (antibody and complement-mediated cytotoxicity tests, the reduction of specific antibody activity of antiserum of known titer, immunofluorescent tests, mixed hemagglutination tests, and their direct isolation), TL antigens but not Thy-1 antigens were formed by the hybrid cells. TL antigens of the hybrids failed to undergo modulation under conditions leading to the modulation of TL antigens of parental ASL-1 cells. Modulation was attempted with TL 1,3, TL 2, or TL 1,2,3 antisera of high titer. thybrid cells were incubated for up to 30 hr in medium with TL antisera. Both direct and indirect immune methods were attempted. These results indicate that cellular mechanisms controlling the expression of TL antigens may be distinguished from the capacity of the cells to undergo modulation.
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PMID:Somatic hybrid of thymus leukemia (. 16 80

A procedure is described by which proteins can be rapidly and efficiently microinjected into large numbers of culture cells. Proteins were first introduced into mammalian red blood cells during hypotonic hemolysis, and the resealed red cells were subsequently fused to culture cells using Sendai virus. In seven experiments, thymidine kinase or 125I-BSA were transferred to culture cells during fusion. Although proteins were used in the present experiments, the microinjection procedure should work equally well for other macromolecules.
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PMID:Microinjection of thymidine kinase and bovine serum albumin into mammalian cells by fusion with red blood cells. 16 73

A number of different techniques to be used for the subtyping of herpes simplex virus (HSV) strains were studied. The strains were inoculated on chorio-allantoic membranes of embryonated eggs and on green monkey kidney (GMK) cells in order that the morphology of plaques produced might be observed. They were classified serologically by determination of K-values and inoculated intracerebrally in mice in order that their pathogenicity for mice might be observed. The inhibitory effect of high concentrations of thymidine on the multiplication of the strains in GMK cells cultures and the heat-stability of the virus-induced thymidine kinases were investigated. Rates of inactivation of the strains in the presence of AgNO3 were compared and, finally, the association of focal liver necrosis in intraperitoneally inoculated mice with the results of the serological typing was observed. The results suggested that the liver necrosis test was simple as well as accurate and useful as a screening typing-test. Reliable results were also obtained serologically and by the method demonstrating differences in the heat-stability of viral thymidine kinase. Using the other methods studied, difficulties to obtain clear-cut or reproducible typing results were encountered.
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PMID:Subtyping of herpes simplex virus. 17 Jul 91

In an attempt to differentiate between thymidine kinase (EC.2.4.1.21) induced by herpesvirus hominis type I (TK I) and type 2 (TK2), the different susceptibilities to the modifying effects of some thymidine analogues proved to be useful criteria: (I)2'-deoxythymidine-5'-triphosphate (dThd-5'-PPP) inhibits TK 2 at a concentration of 0-125 mM by 90%, whereas TK I is inhibited at 4-03 mM by 50%. (2) 2'-deoxythymidine-5'-monophosphate (dThd-5'-P) competitively inhibits TK 2 at all concentrations tested. On the other hand, the direction of its effect on TK I is concentration dependent: at 500 mum it stimulates and at 8 mM inhibits TK I activity. During enzyme kinetic studies, TK I displays substrate inhibition which is reversed by dThd-5'-P. This result explains the stimulating effect of dThd-5'-P at 500 muM. This phenomenon suggests the existence on the enzyme molecule of a second binding site for dThd which mediates substrate inhibition and which can be occupied also by dThd-5'-P. After polyacrylamide gel electrophoresis of TK I, the stimulation by dThd-5'-P disappears, suggesting the separation of the second binding site from the catalytic centre.
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PMID:Regulation by thymidine monophosphate and other nucleotides of thymidine kinase activity in extracts from primary rabbit kidney cells infected by HSV types 1 and 2. 17 38


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