Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Until recently the Theta-class glutathione S-transferases (GSTs) were largely overlooked due to their low activity with the model substrate 1-chloro-2,4-dinitrobenzene (CDNB) and their failure to bind to immobilized glutathione affinity matrices. Little is known about the number of genes in this class. Recently, Pemble et al. (Biochem J. 300: 271-276, 1994) reported the cDNA cloning of a human Theta-class GST, termed GSTT1. In this study, we describe the molecular cloning of a cDNA encoding a second human Theta-class GST (GSTT2) from a lambda gt11 human liver 5'-stretch cDNA library. The encoded protein contains 244 amino acids and has 78.3% sequence identity with the rat subunit 12 and only 55.0% identity with human GSTT1. GSTT2 has been mapped to chromosome 22 by somatic cell hybrid analysis. The precise position of the gene was localized to subband 22q11.2 by in situ hybridization. The absence of other regions of hybridization suggests that there are no closely related sequences (e.g., reverse transcribed pseudogenes) scattered throughout the genome and that if there are closely related genes, they must be clustered near GSTT2. Southern blot analysis of human DNA digested with BamHI shows that the size of the GSTT2 gene is relatively small, as the coding sequence falls within a 3.6-kb BamHI fragment.
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PMID:Molecular cloning of a cDNA and chromosomal localization of a human theta-class glutathione S-transferase gene (GSTT2) to chromosome 22. 778 71

In this study, we have isolated and characterized a gene and cDNA encoding a mouse Theta class GST. The gene, mGSTT2, spans approximately 3.1 kb and is composed of five exons interrupted by four introns. The gene was localized to Chromosome 10B5-C1 by in situ hybridization. Southern blot analysis of mouse genomic DNA suggests that there is only one copy of mGSTT2 in the mouse genome. The cDNA derived from mGSTT2 was isolated from a mouse liver cDNA library and has an open reading frame of 732 bp encoding a peptide of 244 amino acids with a calculated molecular weight of 26,676 Da. The encoded protein shares amino acid sequence identities of 92, 77, 51, and 55% with rat subunit Yrs, human subunit GSTT2, rat subunit 5, and human subunit GSTT1, respectively.
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PMID:Characterization of a cDNA and gene encoding the mouse theta class glutathione transferase mGSTT2 and its localization to chromosome 10B5-C1. 861 93

Two loci encoding Theta class glutathione transferases (GSTs) have been identified in humans. In situ hybridization studies have localized the GSTT1 gene to 22q11.2. This is the same band to which we previously localized the GSTT2 gene. This finding confirms the trend for human GST genes to be found in class-specific clusters.
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PMID:Chromosomal localization of the gene for the human theta class glutathione transferase (GSTT1). 861 95

A cDNA encoding the human Theta-class glutathione transferase GSTT2-2 was expressed in Escherichia coli as a ubiquitin fusion protein. The co-translational removal of the ubiquitin by a cloned ubiquitin-specific protease, Ubp1, generates enzymically active GSTT2-2 without any additional N-terminal residues. The recombinant isoenzyme was purified to apparent homogeneity by DEAE anion-exchange, gel filtration, dye ligand chromatography and high resolution anion-exchange chromatography on Mono Q FPLC. The recombinant enzyme had significant activity with a range of substrates, including cumene hydroperoxide and 1-menapthyl sulphate. The activity of GSTT2-2 with a range of secondary lipid peroxidation products such as the trans,trans-alka-2,4-dienals and trans-alk-2-enals, as well as its glutathione peroxidase activity with organic hydroperoxides, suggest that it may play a significant role in protection against the products of lipid peroxidation.
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PMID:Purification and characterization of a recombinant human Theta-class glutathione transferase (GSTT2-2). 864 50

Two murine Theta-class glutathione S-transferases (GSTs), mGSTT1 and mGSTT2, have been cloned and sequenced. The murine cDNAs, together with the published sequences of the rat and human enzymes, were used to design oligonucleotide probes in order to determine the distribution of mRNA for these enzymes in the liver and lung of rat, mouse and human. The mRNA distribution was compared with that of enzyme protein determined with an antibody to rat GSTT2-2. Both the antibody and the oligonucleotide probes gave the same distribution patterns. Both enzymes were present at significantly higher concentrations in mouse tissues than in rat or human tissues. In mouse liver, both enzymes were localized in specific cell types and in nuclei. Although the distribution of GSTT2-2 in rat liver was similar to that seen in the mouse, GSTT1-1 was not localized in a specific cell type or in the nuclei of either rat or human liver. In the lungs, very high concentrations of the Theta enzymes were present in mouse-lung Clara cells and ciliated cells, with much lower levels in the Clara cells only of rat lung. Low levels of human transferase GSTT1-1 were detected in a small number of Clara cells and ciliated cells at the alveolar/ bronchiolar junction. The relative activities between species, and the cellular and sub-cellular distribution within the liver and lungs of each species, provides an explanation for the species-specificity of methylene chloride, a mouse-specific carcinogen activated by glutathione S-transferase GSTT1-1.
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PMID:The distribution of theta-class glutathione S-transferases in the liver and lung of mouse, rat and human. 876 85

A tertiary model of the human GSTT2 Theta class glutathione transferase is presented based on the recently solved crystal structure of a related thetalike isoenzyme from Lucilia cuprina. Although the N-terminal domains are quite homologous, the C-terminal domains share less than about 20% identity. The model is used to consolidate the role of Ser 11 in the active site of the enzyme as well as to identify other residues and mechanisms of likely catalytic importance. The T2 subfamily of theta class enzymes have been shown to inactivate reactive sulfate esters arising from arylmethanols. A possible reaction pathway involving the conjugation of glutathione with one such sulfate ester, 1-menaphthyl-sulfate, is described. It is also proposed that the C-terminal region of the enzyme plays an important role in allowing substrate access to the active site.
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PMID:Homology model for the human GSTT2 Theta class glutathione transferase. 903 17

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been claimed to reduce cancer rates in oesophagus, stomach and colon of humans and laboratory animals. Recently we showed that dietary administration of NSAIDs enhanced glutathione S-transferase (GST) class alpha, mu and pi levels in the upper part of the rat gastrointestinal tract, with minor effects in the colon. Enhancement of GSTs, a family of detoxification enzymes consisting of class alpha, mu, pi and theta isoforms, might be one of the mechanisms leading to cancer prevention. The recently cloned GST class theta levels have not yet been studied in this respect. We now investigated whether the NSAIDs indomethacin, relafen, sulindac, ibuprofen, piroxicam, and acetyl salicylic acid (ASA), incorporated individually into the diet at 25, 200, 320, 400, 400 and 400 mg/kg, respectively, affect gastrointestinal GSTT1-1 and GSTT2-2 levels in male Wistar rats. GSTT1-1 and GSTT2-2 levels were determined in cytosolic fractions of oesophagus, gastric, small intestinal and colonic mucosa and liver by densitometrical analyses of Western blots after immunodetection with a monoclonal (GSTT1-1) or a polyclonal (GSTT2-2) antibody. Gastric GSTT2-2 levels were induced by ibuprofen (1.6x) and indomethacin (1.5x), and colonic levels were induced by ASA (1.7x). Colonic GSTT1-1 levels were elevated by all NSAIDs tested except for relafen (1.5-6.4x). In conclusion, enhancement of colonic GSTT1-1 levels seems to be a common working mechanism of NSAIDs. Enhanced enzyme activity, which may result from these higher GSTT1-1 levels, might lead to a more efficient detoxification of potential carcinogens and hence contribute to the prevention of colon carcinogenesis.
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PMID:Nonsteroidal anti-inflammatory drugs enhance glutathione S-transferase theta levels in rat colon. 972 37

The structure and organization of the human Theta-class glutathione S-transferase (GST) genes have been determined. GSTT1 and GSTT2 are separated by approx. 50 kb. They have a similar structure, being composed of five exons with identical exon/intron boundaries. GSTT1 is 8.1 kb in length, while GSTT2 is only 3.7 kb. The GSTT2 gene lies head-to-head with a gene encoding d-dopachrome tautomerase (DDCT), which extends over 8.5 kb and contains four exons. The sequence between GSTT2 and DDCT may contain a bidirectional promoter. The GSTT2 and DDCT genes have been duplicated in an inverted repeat. Sequence analysis of the duplicated GSTT2 gene has identified an exon 2/intron 2 splice site abnormality and a premature translation stop signal at codon 196. These changes suggest that the duplicate gene is a pseudogene, and it has been named GSTT2P.
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PMID:Structure and organization of the human theta-class glutathione S-transferase and D-dopachrome tautomerase gene complex. 972 70

We have isolated and characterized a cDNA and partial gene encoding a murine subfamily 1 Theta class glutathione transferase (GST). The cDNA derived from mouse GSTT1 has an open reading frame of 720 bp encoding a peptide of 240 amino acids with a calculated molecular mass of 27356 Da. The encoded protein shares only 51% deduced amino acid sequence identity with mouse GSTT2, but greater than 80% deduced amino acid sequence identity with rat GSTT1 and human GSTT1. Mouse GSTT1-1 was expressed in Escherichia coli as an N-terminal 6x histidine-tagged protein and purified using immobilized-metal affinity chromatography on nickel-agarose. The yield of the purified recombinant protein from E. coli cultures was approx. 14 mg/l. Recombinant mouse GSTT1-1 was catalytically active towards 1, 2-epoxy-3-(p-nitrophenoxy)propane, 4-nitrobenzyl chloride and dichloromethane. Low activity towards 1-menaphthyl sulphate and 1-chloro-2,4-dinitrobenzene was detected, whereas mouse GSTT1-1 was inactive towards ethacrynic acid. Recombinant mouse GSTT1-1 exhibited glutathione peroxidase activity towards cumene hydroperoxide and t-butyl hydroperoxide, but was inactive towards a range of secondary lipid-peroxidation products, such as the trans-alk-2-enals and trans,trans-alka-2,4-dienals. Mouse GSTT1 mRNA is most abundant in mouse liver and kidney, with some expression in intestinal mucosa. Mouse GSTT1 mRNA is induced in liver by phenobarbital, but not by butylated hydroxyanisole, beta-napthoflavone or isosafrole. The structure of mouse GSTT1 is conserved with that of the subfamily 2 Theta class GST genes mouse GSTT2 and rat GSTT2, comprising five exons interrupted by four introns. The mouse GSTT1 gene was found, by in situ hybridization, to be clustered with mouse GSTT2 on chromosome 10 at bands B5-C1. This region is syntenic with the location of the human Theta class GSTs clustered on chromosome 22q11.2. Similarity searches of a mouse-expressed sequence tag database suggest that there may be two additional members of the Theta class that share 70% and 88% protein sequence identity with mouse GSTT1, but less than 55% sequence identity with mouse GSTT2.
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PMID:Gene structure, expression and chromosomal localization of murine theta class glutathione transferase mGSTT1-1. 985 36

The expression of different isoenzymes of glutathione transferase (GST), i.e. the cytosolic subunits GSTA1/A2, A3, A4, A5, M1/2, M2 and P1, T2, and the microsomal GST in follicles of different sizes and in corpora lutea from porcine ovary, was investigated by Western blotting. No immunoreactivity was obtained with anti-rat GSTT2 or anti-rat microsomal GST polyclonal antibodies. In contrast, GSTA1/A2, A3, A4, A5, M1/2, M2 and P1 are all expressed in the cytosol from porcine ovaries. In general, the highest levels of these GST isoenzymes were present in the cytosol from corpora lutea, in agreement with measurements of activity towards 1-chloro-2,4-dinitrobenzene. Immunoreactivity with anti-rat GSTP1 was only obtained with follicles. The cytosolic GSTs from follicles and corpora lutea were affinity purified on glutathione-Sepharose and separated by reversed-phase high-performance liquid chromatography in order to quantitate the different subunits. A peak corresponding to the class pi subunit was present in follicles. This peak was also seen with corpora lutea, although at very low level. There were four peaks containing class mu subunits. The remaining peaks were concluded to contain the class alpha subunits, except for two peaks which are suggested to contain proteins other than GSTs. The levels of the different subunits were quantitated on the basis of the areas under the peaks and the relative amounts in follicles of different sizes and in corpora lutea corresponded well with the Western blot analysis.
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PMID:Expression of glutathione transferase isoenzymes in the porcine ovary in relationship to follicular maturation and luteinization. 1019 May 43


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