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

---

Query: EC:2.5.1.18 (glutathione S-transferase)
22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pulse-chase technique was employed to determine the synthesis of the subunits of ligandin (glutathione S-transferase 1-2) by isolated hepatocytes. Ligandin comprised 2.5-3% of the total proteins synthesized. A slightly higher incorporation of [35S]methionine into the 22 k than the 25 k subunit was observed. However, the ratio of [35S]methionine incorporation into the subunits remained constant throughout the chase period, suggesting that, in spite of the considerable sequence homology, the conversion of 25 k to 22 k subunit does not occur in vivo.
...
PMID:Synthesis of subunits of ligandin by isolated hepatocytes. 359 70

A monoclonal antibody against rat liver glutathione S-transferase B, which consists of subunits Ya (Mr 27,000) and Yc (Mr 29,500), was produced in a mouse hybridoma system. The monoclonal antibody, BE6Yc1, was of the immunoglobulin G1 class and specifically recognized glutathione S-transferase B showing no cross-reactivity against the dimeric form of Ya, ligandin, in enzyme-linked immunosorbent assay. A glutathione S-transferase B-BE6Yc1 monoclonal antibody complex was identified from the zymogram pattern on starch gel electrophoresis. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis of rat liver glutathione S-transferase B, followed by Western blotting with BE6Yc1 antibody, a single polypeptide with a molecular weight of 29,500, identical to the Yc subunit of rat liver glutathione S-transferase B, was identified. The antibody showed no cross-reactivity with the Ya subunit with a molecular weight of 27,000 of either glutathione S-transferase B or ligandin. These results show that there are at least two distinct epitopes in the Ya and the Yc subunit. The monoclonal antibody did not block the catalytic activity of glutathione S-transferase B toward cumene hydroperoxide and possibly also 1-chloro-2,4-dinitrobenzene. Quantitative differences in expression of the Yc subunit of glutathione S-transferases were demonstrated in extracts of various normal tissues with the BE6Yc1 antibody by Western blot analysis. The Yc subunit was found to be present at much lower levels in kidney, small intestine, spleen, and lung than in liver and testis.
...
PMID:A monoclonal antibody specific for the Yc subunit of rat liver glutathione S-transferase B. 375 78

The ability of different lipid-binding proteins in liver cytosol to affect enzyme activities in bile-acid biosynthesis was studied in whole microsomes (microsomal fractions) and mitochondria and in purified enzyme systems. Sterol carrier protein2 stimulated the 7 alpha-hydroxylation of cholesterol and the 12 alpha-hydroxylation of 5 beta-cholestane-3 alpha, 7 alpha-diol in microsomes and the 26-hydroxylation of cholesterol in mitochondria 2-3-fold. It also stimulated the oxidation of 5-cholestene-3 beta, 7 alpha-diol into 7 alpha-hydroxy-4-cholesten-3-one in microsomes. The stimulatory effect of sterol carrier protein2 was much less with purified cholesterol 7 alpha- and 26-hydroxylase systems than with microsomes and mitochondria. No stimulatory effect of sterol carrier protein2 was observed with purified 12 alpha-hydroxylase and 3 beta-hydroxy-delta 5-C27-steroid oxidoreductase. Sterol carrier protein (fatty-acid-binding protein), 'DEAE-peak I protein' [Dempsey, McCoy, Baker, Dimitriadou-Vafiadou, Lorsbach & Howards (1981) J. Biol. Chem. 256, 1867-1873], ligandin (glutathione transferase B) and serum albumin had no marked stimulatory effects in either crude or in purified systems. The results suggest that sterol carrier protein2 facilitates the introduction of the less-polar substrates in bile-acid biosynthesis to the membrane-bound enzymes in crude systems in vitro. The broad substrate specificity appears, however, not to be consistent with a specific regulatory function for sterol carrier protein2 in bile-acid biosynthesis.
...
PMID:The role of sterol carrier protein2 and other hepatic lipid-binding proteins in bile-acid biosynthesis. 380 Sep 67

The biliary secretion of methylmercury was investigated in male rats which were given i.p. 400 mumoles/kg azathioprine or 96 mumoles/kg benziodarone 2 hr after the i.v. injection of 5 mumoles/kg MeHgCl. A group of rats were given 400 mg/kg trans-stilbene oxide (TSO) for 4 days before treatment with 10 mumoles/kg MeHgCl. A common link between these three compounds is their interference with ligandin. Azathioprine is a competitive inhibitor of glutathione S-transferase, benziodarone is covalently bound to ligandin and TSO is an inducer of liver ligandin. Although only azathioprine depletes liver GSH stores, both azathioprine and benziodarone inhibited the biliary secretion of methylmercury. As there is published proof that the reaction of MeHg+ with GSH does not require enzymatic help, the inhibitory effect of azathioprine and benziodarone confirms the role of ligandin in the transport of methylmercury or its GSH complex. However, the biliary secretion of methylmercury was increased only slightly by TSO pretreatment, but when 2 hr after the injection of MeHgCl animals received 2 mmoles/kg GSH, secretion increased twice as much in TWO pretreated than in control rats. This indicates the dual dependance of biliary methylmercury secretion on liver GSH and ligandin.
...
PMID:The dependence of biliary methylmercury secretion on liver GSH and ligandin. 387 12

The major glutathione S-transferase from larvae of Galleria mellonella binds a number of synthetic triphenylmethane dyes with dissociation constants of the order of 10(-6) M or less. The organ distribution of the enzyme activity does not parallel the uptake of such dyes by the insect's organs in vivo. The affinity of the protein for such dyes is decreased by about an order of magnitude by the presence of glutathione in normal physiological concentration. This appears to be the cause of this protein's lack of efficacy as a 'ligandin' in vivo. The dyes appear to be acting as ineffective substrate analogues, binding at the catalytic site and impeding, in a reciprocal fashion, the binding of glutathione. Fluorescence-quenching titration and kinetic experiments together indicate the existence of a single ligand-binding and catalytic site per dimeric enzyme molecule.
...
PMID:Suppression of high-affinity ligand binding to the major glutathione S-transferase from Galleria mellonella by physiological concentrations of glutathione. 395 38

Evidence is presented that ligandin, an intracellular protein involved in the binding of such anions as bilirubin, indocyanine green, and penicillin, is identical to glutathione S-transferase B (EC 2.5.1.18), an enzyme catalyzing the conjugation of glutathione with such electrophiles as 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, iodomethane, ethacrynic acid, and bromosulfophthalein. The proteins, isolated by distinct methods, have the same specificity for substrates and for ligands, react in identical fashion to antibody produced against ligandin, bear entirely similar physical characteristics and amino acid composition, and are both induced in response to phenobarbital. Indocyanine green, one of the ligands that is not effective as a substrate, was shown to competitively inhibit the conjugation reaction. It is suggested that specificity is directed toward compounds with electrophilic sites.
...
PMID:The identity of glutathione S-transferase B with ligandin, a major binding protein of liver. 413 4

Using gel filtration, the binding of both glutathione and Bromsulphthalein (BSP) to a liver-soluble protein was found to be identical. BSP-conjugating activity (glutathione S-aryltransferase) was present only in the fractions corresponding to the two protein-bound markers. Using a highly sensitive assay, with 3,4-dichloronitrobenzene, the pattern of glutathione S-aryltransferase activity was found to coincide with Y protein. This evidence suggests that Y protein, or ligandin, has a dual role in hepatic transport: a specific enzymic function in the conjugation of certain anions with glutathione in addition to a transport function in the intracellular binding of organic anions.
...
PMID:Role of hepatic anion-binding protein in bromsulphthalein conjugation. 471 80

Qualitative and quantitative changes in glutathione S-transferase (GSH-T) were studied in human hepatocellular carcinoma. GSH-T specific activity (mumoles per min per mg protein) was variably reduced in hepatocellular carcinoma. Similar changes were seen in "cationic" GSH-T (ligandin) concentration determined by radioimmunoassay. Immunohistochemical studies with antihuman liver ligandin suggest that positive staining was more frequently found in well-differentiated tumors. The relative activities of "cationic," "neutral," and "anionic" transferases (pI greater than 7.5) activity ranged from virtually absent to near normal values. "Neutral" (pI 6 to 6.5) and "anionic" (pI less than 5.4) species were present more often in tumors than in normal liver. In two cases, normal liver tissue and tumor were obtained from the same patient. In one, only quantitative differences were present, while in the other "cationic" and "neutral" GSH-Ts were present in the normal liver tissue while both "cationic" and "anionic" species were found in the tumor. Our studies indicate that qualitative as well as quantitative changes of GSH-T occur in human hepatocellular carcinoma.
...
PMID:Glutathione S-transferase in human hepatocellular carcinoma. 618 52

We describe the construction and characterization of a cDNA plasmid for one of the rat liver glutathione S-transferase subunits. Poly(A)-RNA isolated from rat livers was enriched for glutathione S-transferase mRNA activity and used as templates to synthesize double stranded cDNA. The double stranded cDNAs were annealed to pBR322 through terminal deoxynucleotidyl transferase generated GC-tails followed by transformation into E. coli. Several candidate clones were selected by colony hybridization using polynucleotide kinase labeled liver and testis poly(A)-RNA probes. These candidate clones were further characterized by hybrid-selected translation of mRNA followed by immunoprecipitation and SDS gel electrophoresis. The positive clone, pGTR112 was mapped with restriction endonuclease analysis and sequenced by the chemical method of Maxam and Gilbert. The largest upen reading frame contains 142 amino acids very rich in Arg and Lys residues. The C-terminal residue phenylalanine of this open reading frame is consistent with what was reported for one of the ligandin subunits by Bhargava et al., (J. Biol. Chem. 253, 4116-4119, 1978). Among the 352 nucleotides covered by both pGTR112 and pGST94 described by Kalinyak and Taylor (J. Biol. Chem. 257, 523-530, 1982), there are only 9 nucleotide differences resulting in four changes of amino acid sequences.
...
PMID:Cloning and sequence analysis of a cDNA plasmid for one of the rat liver glutathione S-transferase subunits. 629 39

The formation of an aflatoxin B1-reduced glutathione (AFB1-GSH) conjugate in in vitro systems has been examined. AFB1 was activated by a chicken liver microsomal system and factors affecting the subsequent conversion to the AFB1-dihydrodiol or conjugation with GSH were investigated by HPLC. A requirement for glutathione S-transferase in the formation of the AFB1-GSH conjugate was observed. Studies using CM-cellulose columns showed the fractions containing glutathione S-transferase B activity were the most effective in catalysing the formation of the AFB1-GSH conjugate. The possibility of changes in the level of AFB1-GSH conjugate production in the liver during carcinogenesis by AFB1 has been examined. It has been found, using freshly isolated rat hepatocytes, that low level feeding with AFB1 in vivo increases the production of the conjugate in vitro. Further increases in the production of the conjugate by hepatocytes in vitro, accompanying increases in the preneoplastic lesions, are achieved by partially hepatectomising the AFB1-fed animals. Partial hepatectomy of control-fed animals yielded no similar changes. The AFB1/partial hepatectomy treatment resulted in increased levels of all the glutathione S-transferase activities fractionated on CM-cellulose. Macromolecular binding of AFB1 and/or of its metabolites was detected in the fractions containing glutathione S-transferase activity, but there was no evidence for a greater binding in the glutathione S-transferase B/ligandin containing fractions. Furthermore fractionation on Sephadex G-75 indicated a predominance of binding of AFB1 to proteins of a higher molecular weight than the glutathione S-transferases, although some binding in the molecular weight range of the latter was observed.
...
PMID:The requirement for glutathione S-transferase in the conjugation of activated aflatoxin B1 during aflatoxin hepatocarcinogenesis in the rat. 641 67


<< Previous 1 2 3 4 5 6 7 8 Next >>

---