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

A method for gene transfer by means of interphase nuclei encapsulated within lipid membranes was developed. The method was based on passage of interphase nuclei through a layer of organic solvents containing phospholipids. Evidence was obtained indicating that the nuclei become surrounded by a protective phospholipid membrane: measurements of bound labelled or non-labelled phospholipids; decrease in the permeability of lipid-encapsulated nuclei for high molecular compounds; visualization by direct electron microscopy. Lipid-encapsulated nuclei of mink fibroblasts were used for transformation of mutant mouse LMTK- cells (deficient for thymidine kinase). The frequency of occurrence of HAT-resistant colonies/recipient cell was 1.9 X 10(-5). Biochemical analysis of 14 independent clones demonstrated that they all contained TK1 of mink origin. Analysis of 15 other biochemical markers located on 12 of the mink chromosomes revealed the activities of mink galactokinase (a syntenic marker) in 5 transformed clones, and that of mink aconitase-1 (the marker of mink chromosome 12) in 1 clone. No cytogenetically visible donor chromosomes were identified in the transformed clones. Nine transformed clones were tested for the stability of the TK+ phenotype; of these, the phenotype was expressed stably in 3 and unstably in 6. The method suggested is similar to the gene transfer procedure using total DNA. Its advantage is in ensuring efficient gene transfer and donor DNA integrity.
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PMID:Transfer of mink genes into mouse cells by means of isolated lipid-encapsulated nuclei. 386 8

Chromosome-mediated gene transfer (CMGT) of the human genes for hypoxanthine phosphoribosyl transferase (HPRT) and cytosol thymidine kinase (TK1) into HPRT deficient mouse A9 cells or TK deficient Swiss mouse 3T3TK- cells was found to occur at frequencies at least one order of magnitude higher than DNA-mediated gene transfer (DMGT). The frequency of CMGT into 3T3TK- cells was reduced by more than an order of magnitude by a posttreatment of the recipient cells with dimethyl sulphoxide (DMSO). After CMGT, expression of the non-selected genes coding for galactokinase (GALK) and acid alpha-glucosidase (GAA), both syntenic with TK1, was observed in a number of transformants. From the pattern of cotransfer, a tentative gene ordering of CENTROMERE-GALK-TK1-GAA on human chromosome 17 was deduced. Chromosome-mediated cotransfer of X-linked human phosphoglycerate kinase (PGK) with HPRT was observed in two out of 33 A9 transformants analysed. DNA-mediated cotransfer of a syntenic gene was only observed for GALK, cotransferred with TK1 in two out of 18 TK+ transformants of mouse LTK- cells. Therefore, with murine cells as recipients of human donor genetic material, CMGT results in a higher frequency of transfer and a higher incidence of cotransfer of syntenic genes than DMGT using cellular DNA in the same cell system.
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PMID:Cotransfer of syntenic human genes into mouse cells using isolated metaphase chromosomes or cellular DNA. 388 35

Chinese hamster cells in culture were treated with various concentrations of thymidine, 5-bromodeoxyuridine, trifluorothymidine, and 2-deoxy-D-galactose. Selection was made for deficiencies in the activities of galactokinase and thymidine kinase. Selection in the presence of thymidine, 5-bromodeoxyuridine, and trifluorothymidine was expected to produce clones deficient in thymidine kinase only, whereas those deficient in galactokinase were expected to be selected in the presence of 2-deoxy-D-galactose. However, it was found that clones growing in the presence of these inhibitors were frequently deficient in both enzymes. Or if a clone was deficient in only one, the deficiency frequently was not expected according to the selection procedure. This indicates some sort of coordinate relationship between the two gene loci, GALK and TK1, which specify galactokinase and thymidine kinase, respectively. GALK and TK1 are linked in all primates and rodents in which linkage determinations have been made. It is therefore probable that this linkage has been conserved for a long period of time. It is suggested that the apparent relationship between the two genes shown by the data presented here, as well as by others, supports the conclusion that linkage has been conserved by natural selection and is therefore not fortuitous.
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PMID:A coordinate relationship between the GALK and the TK1 genes of the Chinese hamster. 393 78

The susceptibility of mice of different ages (from four to 28 days) to infection with herpes simplex virus type 1 (HSV-1) mutants inoculated onto scarified corneas was studied. The TK+ isolate from wild type virus was pathogenic in mice of all age groups. An HSV-1 mutant (designated TK1/4) with a less active thymidine kinase (TK) gene expressing 25 per cent of the TK activity of the TK+ isolate was pathogenic for mice up to 10 days of age. In older mice, virus pathogenicity was dependent on the inoculum dose: increasing the TK1/4 virus dose tenfold raised the level of TK activity and thus the virulence of the virus. A TK- mutant with no TK activity was pathogenic for four to eight day old mice that have TK activity in the brain, but not in older mice. Thus, resistance to HSV-1 that is age-dependent in mice can be determined by the extent to which the virus strain is liable to express its TK gene and by the amount of TK activity present in the brain.
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PMID:Neurovirulence of herpes simplex virus type 1 depends on age in mice and thymidine kinase expression. 631

The thymidine kinase isoenzyme profile was determined in peripheral blood mononuclear cells and splenic tissue from 4 patients with hairy cell leukaemia, in order to assess the proliferative state of the hairy cell. The predominance of TK1 activity in all 4 spleens and in 2 out of 3 peripheral blood mononuclear cells examined, indicates that the hairy cell has significant proliferative capacity when compared to the neoplastic cell in other chronic lymphoproliferative disorders. It is suggested, in view of the heterogeneity in peripheral blood mononuclear TK isoenzyme types, that more extensive studies are warranted to examine the relationship between peripheral blood mononuclear TK1 activity and the occurrence of progressive disease in post-splenectomy patients.
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PMID:Fetal thymidine kinase (TK1) in hairy cell leukaemia. 683 28

Human thymidine kinase TK1 isoenzyme has been purified 1800-fold from placenta to a specific activity of 2.9 nmoles/min/mg of protein. The rapid purification procedure includes affinity chromatography on a thymidine-Sepharose column. At all stages of purification, the enzyme showed irreversible lability. The native molecular weight was determined to be 45000. Human placental TK1 exhibited specificity for ATP and thymidine as substrates, and significant inhibition was found only with thymidine nucleotides. TTP was the most effective inhibitor.
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PMID:Human thymidine kinase: purification and some properties of the TK1 isoenzyme from placenta. 698 69

The profile of thymidine kinase isoenzymes was determined in peripheral blood lymphocytes from 14 patients with chronic lymphocytic leukaemia (CLL) and 31 controls. Twelve patients with indolent disease showed TK2 isoenzyme activity, while two patients in whom the disease evolved and two patients who presented with aggressive disease exhibited TK1 isoenzyme activity. The demonstration of TK1 activity in the peripheral blood lymphocytes of clinically aggressive CLL suggests that this isoenzyme may be a useful biochemical marker of such behaviour.
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PMID:Thymidine kinase isoenzymes in chronic lymphocytic leukaemia. 729 90

To determine whether kinase (TK) isozyme status adds clinically useful information in adult non-Hodgkin's lymphoma (NHL), we have analyzed peripheral blood plasma and lymphocytes of 44 patients with NHL for either TK1 or TK2 isozyme activity. On the basis of isozyme status, patients could be divided into two groups that did not differ significantly with respect to known determinants for survival. The median survival of patients exhibiting peripheral blood TK1 thymidine kinase activity was 40 wk and that of individuals with TK2 activity was in excess of 200 wk. These data suggest that peripheral blood TK1 isozyme is a useful independent biochemical marker for a subgroup of NHL who respond poorly to current therapy and thus require new therapeutic approaches.
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PMID:Prognostic relevance of thymidine kinase isozymes in adult non-Hodgkin's lymphoma. 729 3

The activities of thymidine kinase (TK) isoenzyme 1 and 2 were examined in extracts of human benign or malignant lymphoid tissue and correlated with degrees of morphological differentiation. TK2 activity occurred in peripheral blood lymphocytes of normal individuals, patients with chronic lymphocytic leukemia, or solid lymphoid tissue, exhibiting either nonneoplastic histological findings or those of diffuse well-differentiated lymphocytic lymphoma. TK1 activity occurred in solid, non-Hodgkin's lymphoma tissue, exhibiting lesser degrees of cellular differentiation, or in peripheral blood lymphocytes of patients with clinical aggressive chronic lymphocytic leukemia or lymphosarcoma leukemia. In non-Hodgkin's lymphoma tissue, the range of TK1 activities correlated broadly with the Rappaport classification, with higher values occurring in tissue exhibiting changes of diffuse poorly differentiated lymphocytic lymphoma or diffuse histiocytic lymphoma.
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PMID:Thymidine kinase isoenzymes in human malignant lymphoma. 744 15

Azidothymidine (zidovudine, AZT) used for treatment of HIV infection blocks the viral reverse transcriptase after phosphorylation by cellular enzymes. The first step in this reaction is the formation of AZT monophosphate, primarily catalyzed by host cytoplasmatic thymidine kinase (TK1). The activity of TK1 was determined in extracts of PHA-stimulated peripheral blood mononuclear cells (PBMCs) from 20 healthy volunteers and 49 HIV-infected patients at different stages of disease. In both groups we found a large intra- and interindividual variation of TK activity. Because TK1 expression is cell cycle regulated the proportion of stimulated cells was determined in the samples and the median thymidine kinase activity calculated. It was 3.0 pmol/mg/min x % S phase in the HIV-seronegative group and 1.1 pmol/mg/min x % S phase in HIV-infected individuals. The difference in thymidine kinase activity is statistically significant (p = 0.0001). The concentration of TK1 protein in the same extracts was also determined by immunoblotting. A positive correlation (r = 0.74) was observed between TK activity and amount of TK1 protein. The reason for this downregulation of TK is still unknown but may be related to the anergy observed in lymphocytes from HIV-infected persons. The reduced capacity for intracellular phosphorylation of AZT in HIV-infected individuals may be an important factor in the emergence of clinical AZT resistance and should also be accounted for in testing AZT resistance in vitro with PBMCs from healthy blood donors.
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PMID:Decreased thymidine kinase levels in peripheral blood cells from HIV-seropositive individuals: implications for zidovudine metabolism. 754 7


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