Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0272170 (SDS)
 50,377 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The gp85 envelope glycoprotein of Epstein-Barr virus (EBV) has a role in the molecular mechanism of infection, enabling fusion between the viral and host cell envelopes, a role in common with the homologous gH glycoproteins in other herpesviruses. A glutathione S-transferase bacterial fusion protein (GST85N-S) was generated, containing 178 amino acids from the C terminus of gp85 and including a known gp85 linear epitope. A panel of EBV-positive human antisera contained no antibodies to linear epitopes presented on the purified GST85N-S protein, indicating that primary protein structure in this region of gp85 is not a B cell target. This bacterial fusion protein was used to raise a rabbit monospecific polyclonal antiserum capable of detecting gp85 in a Western blot. The majority of recombinant baculovirus-expressed gp85 obtained from cell extracts prepared with SDS appeared on Western blots as heterogeneous high M(r) protein aggregates and consistently included 84K, 81K and 70K bands. Recombinant gp85 aggregation was increased by boiling the sample prior to gel electrophoresis. The 84K and 81K proteins were completely sensitive to endoglycosidase H treatment, indicating that these glycosylated species did not undergo further post-translational processing. Immunofluorescence studies revealed that recombinant gp85 was not transported to the insect cell surface. It reacted only with antibodies recognizing denatured gp85 and not with antibody to native gp85. Therefore expression of the gene encoding gp85, BXLF2, alone in the baculovirus expression system is insufficient for the synthesis of a correctly transported, processed, folded and antigenically native form of recombinant gp85.
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PMID:Expression of the Epstein-Barr virus envelope fusion glycoprotein gp85 gene by a recombinant baculovirus. 752 63

We recently reported that phosphatidylinositol (PI) 3-kinase becomes associated with the activated erythropoietin receptor (EpR), most likely through the Src homology 2 (SH2) domains within the p85 subunit of PI-3 kinase and one or more phosphorylated tyrosines within the EpR. We have now investigated this interaction in more detail and have found, based on both blotting studies with glutathione S-transferase-p85-SH2 fusion proteins and binding of these fusion proteins to SDS-denatured EpRs, that this binding is direct. Moreover, both in vitro competition studies, involving phosphorylated peptides corresponding to the amino acid sequences flanking the eight tyrosines within the intracellular domain of the EpR, and in vivo studies with mutant EpRs bearing tyrosine to phenylalanine substitutions, indicate that phosphorylation of Tyr503 within the EpR is essential for the binding of PI 3-kinase. The presence of PI 3-kinase activity in EpR immunoprecipitates from DA-3 cells infected with wild-type but not Y503F EpRs confirms this finding. Our results demonstrate that the SH2 domains of p85 can bind, in addition to their well established Tyr-Met/Val-X-Met consensus binding sequence, a Tyr-Val-Ala-Cys motif that is present in the EpR. A comparison of erythropoietin-induced tyrosine phosphorylations and proliferation of wild-type and Y503F EpR-infected DA-3 cells revealed no differences. However, the PI-3 kinase inhibitor, wortmannin, markedly inhibited the erythropoietin-induced proliferation of both cell types, suggesting that PI 3-kinase is activated in Y503F EpR expressing cells. This was confirmed by carrying out PI 3-kinase assays with anti-phosphotyrosine immunoprecipitates from erythropoietin-stimulated Y503F EpR-infected DA-3 cells and suggested that PI 3-kinase has a role in regulating erythropoietin-induced proliferation, but at a site distinct from the EpR.
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PMID:Phosphorylation of tyrosine 503 in the erythropoietin receptor (EpR) is essential for binding the P85 subunit of phosphatidylinositol (PI) 3-kinase and for EpR-associated PI 3-kinase activity. 755 99

To investigate the failure of high-level production of hepatitis B viral (HBV) surface antigen (HBsAg), including three authentic forms, large (L), middle (M) and major/small (S) HBsAg, in Escherichia coli, we employed the high-expression vector pGEX containing the glutathione S-transferase-encoding gene (GST) to study HBsAg production. Different fragments of HBV DNA containing the entire pre-S1/pre-S2/S region (for L protein), or partial pre-S1, pre-S2, pre-S1/pre-S2 and pre-S2/S region (for M protein), were fused downstream from the GST gene, in order to obtain five plasmids which encode GST-HBsAg fusion proteins. SDS-PAGE analyses revealed that cells containing plasmids with a full-length S region (pGLS and pGMS) produced undetectable GST-HBsAg fusion proteins, in contrast to those cells harboring plasmids without the S region (pGS1, pGS2 and pGS1S2), which synthesized fusion proteins in 3-10% of the total cellular protein. Using an immunoblot method to screen HBsAg production in cells which harbored plasmids derived from exonuclease BAL 31-digested pGLS, we obtained eight positive clones. Nucleotide sequence analyses of plasmids from the positive clones revealed that termination, deletion or frameshift occurred at the regions encoding either the first or the third transmembrane domain of the major HBsAg. Correlation between the production level of GST-HBsAg fusion proteins and their constituent and arrangement of amino acids (aa) at the last 20 aa among 15 clones suggested that the fusion protein ended with a longer stretch of or a higher ratio of hydrophobic aa had a lower production in E. coli.
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PMID:Deletion or alteration of hydrophobic amino acids at the first and the third transmembrane domains of hepatitis B surface antigen enhances its production in Escherichia coli. 764 92

The ryanodine receptor (RyR)/calcium release channel isolated from skeletal muscle terminal cisternae (TC) of sarcoplasmic reticulum (SR) is tightly associated with FK506 binding protein of 12.0 kDa (FKBP12) (Jayaraman et al., (1992) J.Biol.Chem. 267, 9474-9477). In this study, we describe a new method of affinity chromatography for purifying the RyR from skeletal muscle SR based on: 1) its tight association with FKBP12; and 2) the finding that bound FKBP on the RyR can be exchanged with soluble FKBP12 (Timerman et al., (1995) J.Biol.Chem. 270, 2451-2459). Soluble glutathione S-transferase/FKBP12 (GST/FKBP12) fusion protein was first exchanged with bound FKBP12 on the RyR of TC. The TC were then solubilized with CHAPS and the complex of RyR.GST/FKBP12 was specifically adsorbed by glutathione Sepharose 4B and then eluted with glutathione. The RyR, purified by this method, has similar characteristics by SDS-PAGE, radioligand binding and immuno-reactivity as the RyR purified by multiple sequential column chromatography.
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PMID:Affinity purification of the ryanodine receptor/calcium release channel from fast twitch skeletal muscle based on its tight association with FKBP12. 766 46

The major isoenzyme of glutathione S-transferase (GST 1) was purified to homogeneity from cytosolic extracts of Mytilus edulis gill tissue by GSH-agarose affinity chromatography followed by Mono Q ion-exchange f.p.l.c. This enzyme was particularly active with 1-chloro-2,4-dinitrobenzene, ethacrynic acid and cumene hydroperoxide as substrates. Immunoblotting and amino acid sequencing studies indicate that the enzyme belongs to the Pi class of GSTs. A related protein which binds to GSH-agarose was also purified. This GSH-binding protein did not immunoblot with GST antisera and showed no detectable catalytic activity with GST substrates although its N-terminal sequence was similar to Mu-class GSTs. Gel-filtration chromatography indicated that GST 1 is a dimer and the GSH-binding protein a monomer. Mass spectrometry and SDS/PAGE indicate subunit molecular masses of 24 kDa (GST 1) and 25 kDa (GSH-binding protein), respectively. Both proteins have amino acid compositions typical of GSTs.
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PMID:Characterization of a glutathione S-transferase and a related glutathione-binding protein from gill of the blue mussel, Mytilus edulis. 782 22

Microsomal glutathione S-transferase (mGST) was purified to homogeneity from male Sprague-Dawley rat liver, as determined by SDS-PAGE. Removal of Triton X-100 and further separation by reversed phase HPLC revealed two proteins, mGST 1 and mGST 2, in a 1:3 ratio. Analysis of mGST 1 and mGST 2 by electrospray ionization mass spectrometry determined their molecular weights to be 17,354.2 +/- 6.6 and 17,397.9 +/- 6.6, respectively. mGST 1 was in close agreement with the calculated molecular weight of 17,348, as predicted by the previously reported cDNA sequence. Cyanogen bromide digestion and peptide mapping by fast atom bombardment mass spectrometry (FAB-MS) localized the mass increase to the N-terminal peptide, 1-7. FAB-tandem mass spectrometry of this peptide in conjunction with Edman reactions on the intact protein demonstrated the N-terminal alanine to be acetylated.
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PMID:Identification of an N-acetylated microsomal glutathione S-transferase by mass spectrometry. 784 Jul 95

We have previously identified a protein factor, named REKS (Ras-dependent Extracellular signal-regulated kinase/Mitogen-activated protein kinase kinase (MEK) Stimulator), which is necessary for Ras-dependent MEK activation. In this study, we attempted to highly purify and characterize REKS. We have highly purified REKS by successive column chromatographies using a cell-free assay system in which REKS activates recombinant extracellular signal-regulated kinase 2 through recombinant MEK in a guanosine 5'-O-(thiotriphosphate) (GTP gamma S)-Ki-Ras-dependent manner. REKS formed a stable complex with GTP gamma S-Ras; REKS was coimmunoprecipitated with GTP gamma S-Ki-Ras or GTP gamma S-Ha-Ras, but not with GDP-Ki-Ras or GDP-Ha-Ras by an anti-Ras antibody. REKS was absorbed to a GTP gamma S-glutathione S-transferase (GST)-Ha-Ras-coupled glutathione-agarose column but not to a GDP-GST-Ha-Ras-coupled glutathione-agarose column and was coeluted with GTP gamma S-GST-Ha-Ras by reduced glutathione. The minimum molecular mass of REKS was estimated to be about 98 kDa on SDS-polyacrylamide gel electrophoresis. REKS phosphorylated this 98-kDa protein as well as recombinant MEK. REKS was not recognized by any of the anti-c-Raf-1, anti-Mos, and anti-mSte11 antibodies. These results indicate that REKS is a Ras-dependent MEK kinase.
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PMID:Purification and characterization of REKS from Xenopus eggs. Identification of REKS as a Ras-dependent mitogen-activated protein kinase kinase kinase. 785 6

A protein fraction migrating as a M(r) 24 kDa band on SDS-PAGE was isolated by affinity chromatography on glutathione-agarose from a soluble extract of E. granulosus proto-scoleces from sheep(UK). This fraction had glutathione S-transferase activity of 0.4 mumol min-1 mg-1 when measured using a standard synthetic substrate and its determined N-terminal amino acid sequence most closely resembled Mu class glutathione S-transferases. In addition, protoscoleces from the distinct sheep and horse E. granulosus strains showed a different pattern of glutathione-binding proteins: the M(r) 24 kDa species was obtained in both cases whereas an additional band of slightly faster electrophoretic mobility was isolated from horse(UK) protoscoleces.
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PMID:Isolation and biochemical characterisation of a glutathione S-transferase from Echinococcus granulosus protoscoleces. 788 40

The human regulatory subunit RI beta of cAMP-dependent protein kinases was expressed in Escherichia coli as a fusion protein with glutathione S-transferase. Purification was performed by affinity chromatography on glutathione-agarose beads after cleavage with thrombin. The human recombinant RI beta protein migrated at 55 kDa on SDS-PAGE and displayed immunoreactivity with an anti-human RI beta antiserum. Furthermore, the purified recombinant RI beta protein was shown to exist as a dimer that was able to form holoenzyme with the catalytic subunit C alpha. The rate of RI beta 2C alpha 2 holoenzyme formation was faster in the presence than in the absence of MgATP. The kinase activity measured before and after adding cAMP to the holoenzyme showed that the presence of cAMP resulted in holoenzyme dissociation and release of active C alpha-subunit, due to cAMP binding to RI beta. Compared to a RI alpha 2C alpha 2 holoenzyme, the RI beta 2C alpha 2 holoenzyme exhibited a more than twofold higher sensitivity to cAMP. The subcellular localization of RI beta was analyzed in quiescent REF-52 fibroblasts and Wistar rat thyroid (WRT) cells after microinjection of fluorescently labeled proteins into the cytoplasm. A cytoplasmic distribution was observed when free RI beta was injected, whereas free C alpha injected into the cytoplasm appeared in the nucleus. When holoenzymes with labeled RI beta and unlabeled C alpha, or unlabeled RI beta and labeled C alpha, were injected, unstimulated cells showed fluorescence in the cytoplasm of both cell types. REF-52 cells stimulated with 8-bromo-cAMP (8-Br-cAMP) and WRT cells treated with thyrotropin (TSH) showed fluorescence mainly in the cytoplasm when RI beta was the labeled subunit of the in vivo dissociated holoenzyme. In contrast, nuclear fluorescence was evident from the release and translocation of labeled C alpha from the holoenzyme complex after stimulation with 8-Br-cAMP or TSH.
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PMID:Human regulatory subunit RI beta of cAMP-dependent protein kinases: expression, holoenzyme formation and microinjection into living cells. 792 53

The genomic DNA for the two Drosophila genes, gstD1 and gstD21, were engineered for expression in Escherichia coli by polymerase chain reaction using a pair of specially designed primers. This newly designed expression system produced consistently high yields of the recombinant glutathione S-transferases (GSTs), which were purified to electrophoretic homogeneity by S-hexyl-GSH affinity chromatography. Consistent with their differences in size, GST D1 and GST D21 displayed different mobilities on SDS-polyacrylamide gel electrophoresis. Circular dichroism spectrometry revealed some differences in the protein secondary structural organization between the two GST D isozymes. Polyclonal antibodies against GST D1 and GST D21 revealed that they are immunologically distinct from each other. The GST D1 antiserum cross-reacted weakly with GST D21, but the GST D21 antiserum had no detectable cross-reactivity with GST D1. The amino acid sequences of GST D1 and GST D21 have 70% identity. GST D1 is active toward CDNB with 17% of the catalytic efficiency of the human alpha GST121, whereas CDNB is a poor substrate for GST D21. Both GST D1 and GST D21 have similar levels of GSH peroxidase activity against cumene hydroperoxide. Another major difference in substrate specificities between GST D1 and GST D21 is in the activity of 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (DDT) dehydrochlorinase, which exists only in the GST D1 isozyme. This is the first definitive demonstration that DDT dehydrochlorinase activity is an intrinsic property of a Drosophila GST. Our results suggest that GST D1 may play a role in DDT metabolism in Drosophila.
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PMID:Biochemical characterization of Drosophila glutathione S-transferases D1 and D21. 796 18


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