Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.5.1.18 (glutathione S-transferase)
 22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mouse mammary tumor virus (MMTV) protease gene was cloned into pGEX-2T, an Escherichia coli expression vector containing the glutathione S-transferase coding region of Schistosoma japonicum. The chimeric protein was formed by fusion of the glutathione S-transferase with a hexapeptide which contains a thrombin cleavage site, followed by the MMTV protease. Affinity chromatography on a glutathione-Sepharose 4B column was used to isolate the chimeric protein. After thrombin cleavage, the glutathione S-transferase and the protease were separated by gel filtration chromatography on a Sephadex G-75 column. The overall yield of the protease purification procedure was about 1 mg of protease/liter of culture, and the specific activity was 380 pmol/min.micrograms of enzyme. Like other retroviral proteases, the MMTV enzyme was active as a dimer, showed maximum activity at pH between 4 and 6, and could be inhibited by pepstatin A and a phosphinic acid derivative HIV-1 protease inhibitor. Enzymatic characterization of this protease reveals its broad specificity, showing a clear preference for the oligopeptide substrate mimicking the cleavage site at the amino-terminal end of the capsid protein (kcat/Km = 9725.5 M-1.s-1). The chimeric protein was also an active dimer and showed a similar Km (17 microM) for such an oligopeptide, although its kcat was about 10 times smaller. Autocatalytic processing of the MMTV protease was observed after expression of clones containing the natural cleavage site, as it occurs at the amino-terminal end of the viral protease, instead of the thrombin-sensitive sequence.
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PMID:Purification and characterization of the mouse mammary tumor virus protease expressed in Escherichia coli. 133 Nov 10

Monoclonal antibodies raised against the 85-kDa subunit (p85) of bovine phosphatidylinositol (PI) 3-kinase were found to recognize uncomplexed p85 or p85 in the active PI 3-kinase. Immunoprecipitation studies of Chinese hamster ovary cells, which overexpress the human insulin receptor when treated with insulin, showed increased amounts of p85 and PI 3-kinase activity immunoprecipitable with monoclonal anti-p85 antibody and no increase in the tyrosine phosphorylation of p85. Insulin also induced an association of p85 with the tyrosine-phosphorylated insulin receptor substrate 1 (IRS-1) and other phosphorylated proteins ranging in size from 100 to 170 kDa but not with the activated insulin receptor. In vitro reconstitution studies were used to show p85 in the active PI 3-kinase associated with the tyrosine-phosphorylated IRS-1 but not with the activated insulin receptor. Competition studies using synthetic phosphopeptides corresponding to potential tyrosine phosphorylation sites of IRS-1 revealed that phosphopeptides containing YMXM motifs inhibited this association with different potencies, whereas nonphosphorylated analogues and a phosphopeptide containing the EYYE motif had no effect. Src homology region 2 domains of p85 expressed as glutathione S-transferase fusion proteins also bound to tyrosine-phosphorylated IRS-1. These results suggest that insulin causes the association of PI 3-kinase with IRS-1 via phosphorylated YMXM motifs of IRS-1 and Src homology region 2 domains of p85.
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PMID:Insulin-dependent formation of a complex containing an 85-kDa subunit of phosphatidylinositol 3-kinase and tyrosine-phosphorylated insulin receptor substrate 1. 133 90

In rats, N-nitrosodimethylamine (NDMA) and N-nitrosopyrrolidine (NPYR) induce liver tumours and, to a lesser extent, nasal tumours. Polybrominated biphenyls (PBBs) are liver tumour promoters and are highly persistent in tissues of rats. To characterize the development of preneoplastic lesions in the liver and nasal cavity, female Sprague-Dawley rats were initiated with NDMA or NPYR and promoted with Firemaster (FM), a commercial mixture of PBBs. Rats were killed after 30, 120 or 180 days of promotion. Liver and nasal tissues were stained with haematoxylin and eosin and were tested immunohistochemically for glutathione S-transferase placental form (GST-P). Significantly more altered hepatocellular foci (AHF) were evident in rats initiated with NDMA or NPYR and promoted with FM compared with non-promoted groups or rats given only FM. Appreciable numbers of AHF were seen at 120 and 180 days in livers of rats in all other treatment groups, whereas the untreated control rats had no AHF. The percentage volume of the liver occupied by AHF was significantly higher in promoted rats given NDMA than in rats given only NDMA or FM. These results indicate that a single oral dose of PBB can significantly enhance development of AHF in rats initiated with NDMA or NPYR. Preneoplastic lesions in nasal tissues were not detected by staining with GST-P.
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PMID:Development of preneoplastic lesions in the liver and nasal epithelium of rats initiated with N-nitrosodimethylamine or N-nitrosopyrrolidine and promoted with polybrominated biphenyls. 133 35

Development of preneoplastic lesions in the rat liver under the influence of various modifiers was investigated with particular attention to changes in simultaneous expression of altered enzyme phenotype within the lesions (conformity) and proliferation potential. Degree of conformity of marker enzymes such as glutathione S-transferase placental form (GST-P), glucose-6-phosphate dehydrogenase (G6PD), glucose-6-phosphatase, adenosine triphosphatase and gamma-glutamyltranspeptidase was compared with levels of 5-bromo-2-deoxyuridine labeling. After initiation with diethylnitrosamine, rats were administered the hepatopromoter sodium phenobarbital (PB, 0.05%), the antioxidant ethoxyquin (EQ, 0.5%), or a peroxisome proliferator, clofibrate (CF, 1.0%) or di(2-ethylhexyl)-phthalate (0.3%) and killed at week 16 or 32. The PB promoting regimen was clearly associated with increase in the numbers of high conformity class lesions simultaneously expressing three to five enzymes, and elevated proliferation potential. The inhibitor, EQ, in contrast, brought about a time-dependent decrease in conformity so that only 1 or 2 alterations were most commonly observed at week 32. Lesion populations in the peroxisome proliferator- and especially CF-treated cases were characterized by obvious dissociation between degree of conformity and proliferative status. Such treatment-dependent differences were not always correlated with the size of the lesion. The results thus suggested that the conformity and proliferation potential of preneoplastic lesions are dependent on modification treatment. Overall, GST-P was found to be the most reliable marker, although G6PD was less influenced in the peroxisome proliferator cases.
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PMID:Effects of modifying agents on conformity of enzyme phenotype and proliferative potential in focal preneoplastic and neoplastic liver cell lesions in rats. 133 90

Dehydroepiandrosterone (DHEA), a C19 adrenal steroid hormone, induces peroxisome proliferation in liver cells and is hepatocarcinogenic in the rat. The present study deals with the phenotypic properties of DHEA-induced liver lesions. A majority of the altered areas (80-87%), neoplastic nodules (> 94%) and hepatocellular carcinomas (HCC, 80-100%) lacked the marker enzymes gamma-glutamyltranspeptidase and placental form of glutathione S-transferase (GSTP). Northern blot analysis of HCC from 4 rats revealed no detectable GSTP mRNA. These HCC, however, showed a marked decrease in the staining of glucose-6-phosphatase and adenosine triphosphatase. These results indicate that the phenotypic properties of liver tumors induced by DHEA and amphipathic carboxylate peroxisome proliferators are similar.
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PMID:Phenotypic properties of liver tumors induced by dehydroepiandrosterone in F-344 rats. 133 91

We examined expressions of the gap junction proteins, connexin 26 (Cx26) and 32 (Cx32), in preneoplastic and neoplastic lesions during rat hepatocarcinogenesis. A marked reduction in the number of Cx32-positive gap junctions was observed in 17% of the glutathione S-transferase placental form-positive foci, whereas 44% of the foci showed increased expression of Cx26. Most hyperplastic nodules exhibited decreased expression of Cx32, whereas 16% of the nodules showed increased expression of Cx26. In hepatocellular carcinomas, expressions of both Cx32 and Cx26 were significantly reduced. These results suggest that the expressions of Cx32 and 26 are differentially regulated during hepatocarcinogenesis, and that the decrease in Cx32 expression occurs earlier, whereas reduction in Cx26 expression occurs later in association with promotion and progression of carcinogenesis.
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PMID:Differential changes in expression of gap junction proteins connexin 26 and 32 during hepatocarcinogenesis in rats. 133 94

Cigarette smoking is the strongest risk factor for lung cancer, but genetically determined variations in the activities of pulmonary enzyme that metabolize tobacco-derived carcinogens may affect individual risk. To investigate whether these enzymes (e.g., CYP1A-related) can serve as markers for carcinogen-DNA damage, lung tissue specimens were taken during surgery from middle-aged men with either lung cancer or non-neoplastic lung disease. Phase I [aryl hydrocarbon hydroxylase (AHH), ethoxycoumarin O-deethylase (ECOD)] and phase II (epoxide hydrolase, UDP-glucuronosyltransferase, glutathione S-transferase) enzyme activities, glutathione and malondialdehyde contents were determined in lung parenchyma and/or bronchial tissues; some samples were also analyzed for DNA adducts, using 32P-postlabeling. The data were then analyzed for the following: a) differences in metabolic profiles between bronchial and parenchymal lung tissue; b) the effect of recent exposure to tobacco smoke on enzyme inducibility and benzo[a]pyrene metabolism; c) differences in enzyme inducibility between lung cancer and non-lung cancer patients; d) the effect of smoking on metabolism of mutagens in vitro; e) pulmonary DNA adduct levels and AHH activity in lung parenchyma of smokers and ex-smokers; f) lipid peroxidation products in lung tissue from lung cancer and non-lung cancer patients, as related to smoking habits and degree of airway obstruction; and g) prognostic value of AHH pulmonary activity in lung cancer patients. The results demonstrate a pronounced effect of tobacco smoke on pulmonary metabolism of xenobiotics and prooxidant state and suggest the existence of a metabolic phenotype at higher risk for tobacco-associated lung cancer.
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PMID:Carcinogen metabolism in human lung tissues and the effect of tobacco smoking: results from a case--control multicenter study on lung cancer patients. 133 22

A region of feline immunodeficiency virus (FIV)/Glasgow-8 external envelope glycoprotein (env) incorporating the third and fourth variable regions (V3/V4) was cloned, inserted into the pGEX vector and expressed in Escherichia coli to yield milligram quantities of the recombinant polypeptide as a fusion protein with glutathione S-transferase. The fusion protein V3/V4GST was used in lymphocyte proliferation assays, where it consistently caused peripheral blood lymphocytes from naive cats to proliferate in a dose-dependent manner. Other FIV fusion proteins produced under identical conditions (V5GST and p24GST) and glutathione S-transferase alone did not cause proliferation in this system. The monoclonal antibody vpg15, which has been shown to block infection of susceptible cells in vitro, did not decrease the response to V3/V4GST. Human peripheral blood lymphocytes did not proliferate in response to V3/V4GST.
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PMID:A recombinant feline immunodeficiency virus envelope fusion protein stimulates peripheral blood lymphocytes from naive cats to proliferate in vitro. 133 93

A plasmid vector has been constructed that allows the ligation-independent cloning of cDNAs in any reading frame and directs their synthesis in Escherichia coli as glutathione S-transferase-linked fusion proteins. The cloning procedure does not require restriction enzyme digestion of the target sequence and does not introduce any additional sequences between the thrombin cleavage site and the foreign protein. Extended single-stranded tails complementary between the vector and insert, generated by the (3'----5') exonuclease activity of T4 DNA polymerase, obviate the need for in vitro ligation prior to bacterial transformation. This cloning procedure is rapid and highly efficient, and has been used successfully to construct a series of fusion proteins to investigate the sequence requirements for efficient thrombin cleavage.
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PMID:Ligation-independent cloning of glutathione S-transferase fusion genes for expression in Escherichia coli. 133 64

The present study examines the effect of butylated hydroxyanisole (BHA) exposure through mother's milk on some of the hepatic xenobiotic metabolizing enzymes in the F1 offspring. Lactating Swiss albino mice received either a 0.5 or 1% BHA diet during the lactation period. The acid-soluble sulfhydryl content and activities of glutathione S-transferase and glutathione reductase increased significantly (p < 0.01) whereas the activity of glutathione peroxidase decreased significantly (p < 0.01) in the liver of pups exposed to BHA via milk. The hepatic content of cytochrome b5 increased (p < 0.01) while that of cytochrome P-450 decreased (p < 0.01) in the pups of dams which received a 1% BHA diet during lactation.
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PMID:Neonatal modulation of hepatic acid soluble sulfhydryls and xenobiotic metabolizing enzymes in suckling mice exposed translactationally to butylated hydroxyanisole. 134 Apr 32


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