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)

To study the activation and differentiation of murine B cells, we prepared a hybridoma secreting monoclonal antibody, LB429, which can directly induce the proliferation of murine B cells in vitro. LB429 recognizes a B cell specific surface molecule of 45 kDa. It recognizes an epitope of murine CD40 produced as a soluble fusion protein with glutathione S-transferase. LB429 stains COS-7 transfectant with murine CD40 cDNA and mature B-cell lines but does not stain pre-B cell lines. Two color staining demonstrated that the epitope recognized with LB429 appears on the surface of B220+ cells of spleen and bone marrow. LB429 can induce a strong proliferation of murine B cells from spleen in the absence of initial triggering with anti-IgM antibody or with anti-IgM antibody + IL-4. LB429 induced the cell size enlargement and the cell cycle transition of resting B cells as well as lipopolysaccharide (LPS). LB429 and LPS stimulate B cells synergistically in vitro by accumulating 44.7% of cells in S/G2/M phases of cell cycle. However, stimulation of spleen B cells with LB429 resulted in the increase of sIgM high+ sIgD(high)+ B cells, in contrast LPS showed the proliferation of both sIgM(high)+ sIgD(high)+ B cells and sIgM(low)+ sIgD(high)+ B cells. These results suggested that LB429 and LPS cause the proliferation of B cells through different stimulatory pathways. This anti-mouse CD40 antibody (LB429) is a very useful reagent to study the activation and differentiation of B cells in vitro.
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PMID:Anti-CD40 monoclonal antibody induces the proliferation of murine B cells as a B-cell mitogen through a distinct pathway from receptors for antigens or lipopolysaccharide. 755 74

We have isolated a novel member of the mammalian PAK (p21 activated kinase) and yeast Ste20 serine/threonine kinase family from a mouse fibroblast cDNA library, designated mPAK-3. Expression of mPAK-3 in Saccharomyces cerevisiae partially restores mating function in ste20 null cells. Like other PAKs, mPAK-3 contains a putative Cdc42Hs/Rac binding sequence and when transiently expressed in COS cells, full-length mPAK-3 binds activated (GTP gamma S (guanosine 5'-3-O-(thio-triphosphate)-bound) glutathione S-transferase (GST)-Cdc42Hs and GST-Rac1 but not GST-RhoA. As expected for a putative target molecule, mPAK-3 does not bind to an effector domain mutant of Cdc42Hs. Furthermore, activated His-tagged Cdc42Hs and His-tagged Rac stimulate mPAK-3 autophosphorylation and phosphorylation of myelin basic protein by mPAK-3 in vitro. Interestingly, the amino-terminal region of mPAK-3 contains potential SH3-binding sites and we find that mPAK-3, expressed in vitro and in vivo, shows highly specific binding to the SH3 domain of phospholipase C-gamma and at least one SH3 domain in the adapter protein Nck. These results raise the possibility of an additional level of regulation of the PAK family in vivo.
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PMID:Identification of a mouse p21Cdc42/Rac activated kinase. 755 98

Human, Drosophila melanogaster, and Caenorhabditis elegans cDNA clones encoding homologues of a serine(threonine) protein kinase (EC 2.7.1.37) (designated Ndr protein kinase) have been isolated and sequenced. The human and Drosophila cDNAs predict polypeptides of 54 kDa and 52 kDa, respectively, which share approximately 80% amino acid similarity. Northern analysis of human tissues revealed a ubiquitously expressed 3.9-kb transcript. Recombinant GST-Ndr underwent intramolecular autophosphorylation on serine and threonine residues in vitro but failed to transphosphorylate several standard protein kinase substrates. Transfection of the human cDNA into COS-1 cells resulted in the appearance of an intense nuclear staining in cells analyzed by indirect immunofluorescence; deletion mutagenesis identified a short basic peptide, KRKAETWKRNRR, responsible for the nuclear accumulation of Ndr. Thus, Ndr is a conserved and widely expressed nuclear protein kinase. The closest known relative of this previously uncharacterized kinase is Dbf2, a budding yeast protein kinase required for the completion of nuclear division.
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PMID:Molecular cloning and characterization of a conserved nuclear serine(threonine) protein kinase. 776 41

Pleckstrin homology (PH) domains are 90-110 amino acid regions of protein sequence homology that are found in a variety of proteins involved in signal transduction and growth control. We have previously reported that the PH domains of several proteins, including beta ARK1, PLC gamma, IRS-1, Ras-GRF, and Ras-GAP, expressed as glutathione S-transferase fusion proteins, can reversibly bind purified bovine brain G beta gamma subunits in vitro with varying affinity. To determine whether PH domain peptides would behave as antagonists of G beta gamma subunit-mediated signal transduction in intact cells, plasmid minigene constructs encoding these PH domains were prepared, which permit transient cellular expression of the peptides. Pertussis toxin-sensitive, G beta gamma subunit-mediated inositol phosphate (IP) production was significantly inhibited in COS-7 cells transiently coexpressing the alpha 2-C10 adrenergic receptor (AR) and each of the PH domain peptides. Pertussis toxin-insensitive, Gq alpha subunit-mediated IP production via coexpressed M1 muscarinic acetylcholine receptor (M1 AChR) was attenuated only by the PLC gamma PH domain peptide, suggesting that the inhibitory effect of most of the PH domain peptides was G beta gamma subunit-specific. Stimulation of the mitogen-activated protein (MAP) kinase pathway by Gi-coupled receptors in COS-7 cells has been reported to require activation of p21ras and to be independent of protein kinase C. Since several proteins involved in activation contain PH domains, the effect of PH domain peptide expression on alpha 2-C10 AR-mediated p21ras-GTP exchange and MAP kinase activation as well as direct G beta gamma subunit-mediated activation of MAP kinase was determined. In each assay, coexpression of the PH domain peptides resulted in significant inhibition. Increasing G beta gamma subunit expression surmounted PH domain peptide-mediated inhibition of MAP kinase activation. These data suggest that the PH domain peptides behave as specific antagonists of G beta gamma-mediated signaling in intact cells and that interactions between PH domains and G beta gamma subunits or structurally related proteins may play a role in the activation of mitogenic signaling pathways by G protein-coupled receptors.
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PMID:Effect of cellular expression of pleckstrin homology domains on Gi-coupled receptor signaling. 776 89

An early step in GH action involves tyrosine phosphorylation of various cellular proteins. Recently, it has been shown in murine preadipocytes that GH promotes the association of its receptor (the GHR) with and the activation of the JAK2 tyrosine kinase. In this study, we confirmed the human (h) GH-induced association of JAK2 with hGHR in IM-9 cells by coimmunoprecipitation experiments using anti-hGHR serum. We further examined the interaction of JAK2 with the GHR cytoplasmic domain by two lines of investigation. For in vitro studies, we assayed by immunoblotting the ability of cell-derived JAK2 to interact with glutathione S-transferase fusion proteins containing elements of the hGHR cytoplasmic domain. A fusion protein containing the entire hGHR cytoplasmic domain (residues 271-620) specifically associated with JAK2 independent of prior stimulation of cells with hGH. This interaction was not dependent on tyrosine phosphorylation of either partner. Mutational analysis of the hGHR cytoplasmic domain component of the fusions indicated that a membrane-proximal 20-residue region that includes the proline-rich box 1 was necessary for the interaction. This region appeared to cooperate with another region(s), largely in the N-terminal one third of the cytoplasmic domain, to promote full interaction with JAK2. For in vivo reconstitution experiments, wild-type (WT) and mutant rabbit GHRs (rGHRs) along with murine JAK2 were expressed by transient transfection in COS-7 cells. rGHR mutations were confined to the cytoplasmic domain and included C-terminal truncations as well as internal deletions of residues 297-406 and 278-292 (the latter contains box 1). All mutant rGHRs were expressed at the cell surface and bound hGH to a degree similar to the WT rGHR. Receptors were tested for their ability to mediate the hGH-induced immunoprecipitability of JAK2 with phosphotyrosine (APT) antibodies. A rGHR truncated to residue 275 [rGHR-(1-275)], which contains only five cytoplasmic residues, failed to mediate JAK2 APT precipitability in response to hGH. In contrast, WT rGHR; the C-terminal truncations rGHR-(1-542), rGHR-(1-390), and rGHR-(1-317); and the rGHR-(d297-406) deletion mutant maintained this ability. Deletion of the 278-292 box 1-containing region in the context of either rGHR-(d297-406) or WT rGHR eliminated detectable hGH-induced JAK2 APT precipitability. Interestingly, rGHR-(1-292), which includes box 1, was not able to mediate significant hGH-induced JAK2 APT precipitability.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Interaction of the growth hormone receptor cytoplasmic domain with the JAK2 tyrosine kinase. 795 46

Although a role for the beta gamma-subunits of heterotrimeric G proteins (G beta gamma) in signal transduction by several cellular systems has been established, the structural features of cellular proteins interacting with G beta gamma have yet to be fully elucidated. The G beta gamma-binding region of beta-adrenergic receptor kinase (beta ARK), a cytosolic enzyme recruited to the membrane receptor substrate by G beta gamma, has been localized to the carboxyl terminus of the enzyme. Here, we demonstrate that the amino terminus of phosducin, a 33-kDa G beta gamma-binding retinal phosphoprotein, contains sequences homologous with the G beta gamma-binding domain of beta ARK. Accordingly, a glutathione S-transferase-fusion protein containing only the amino-terminal 105 amino acids of phosducin displayed G beta gamma binding ability. This domain of phosducin contains a protein kinase A (PKA) phosphorylation site, and upon phosphorylation, the binding of full-length phosducin to G beta gamma is reduced. In addition, transient expression of phosducin in COS-7 cells significantly inhibits G beta gamma-mediated phosphoinositide hydrolysis. This inhibitory effect is completely reversed by pretreatment of cells with dibutyryl cAMP, an activator of PKA. Thus, the binding of G beta gamma to phosducin can be regulated by PKA-phosphorylation in an intact cell model system.
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PMID:Determination of the G beta gamma-binding domain of phosducin. A regulatable modulator of G beta gamma signaling. 796 75

In order to study the structural details of ligand protein interactions of the human retinoid X receptor alpha (hRXR alpha), the DEF and EF domains of the receptor were expressed as glutathione S-transferase (GST) fusion proteins in Escherichia coli. The fusion proteins were expressed at high levels and were affinity-purified by chromatography over glutathione-agarose. The DEF and EF domains were cleaved from the fusion proteins by digestion with thrombin. Retinoic acid binding was quantitated using two different methods. The apparent dissociation constant (Kd) and the stoichiometry of 9-cis-retinoic acid binding were performed by monitoring quenching of protein fluorescence. To directly compare the binding affinity of the E. coli-derived truncated hRXR alpha with full-length hRXR alpha expressed in transiently transfected COS cells, Scatchard analyses of [3H]9-cis-retinoic acid binding assays were performed. Both methods of analysis indicate that while the cleaved DEF peptide bound 9-cis-retinoic acid tightly, the cleaved EF peptide exhibited variable binding activity between preparations. By fluorimetric analysis, the Kd of the cleaved DEF peptide was estimated to be 3 +/- 0.5 nM with a stoichiometry of 1:1.1 +/- 0.1. By Scatchard analysis, the Kd values for [3H]9-cis-retinoic acid to the GST-hRXR alpha (DEF) peptide and the cleaved DEF peptide were estimated to be 1.8 nM and 5.6 nM, respectively. The estimated molecular mass from high speed sedimentation equilibrium experiments was 36 +/- 2 kDa for the apo-DEF peptide alone and 38 +/- 3 kDa for the holo-DEF peptide complexed with 9-cis-retinoic acid. This suggests that the recombinant ligand binding domain was predominantly in the monomer form. However, dimers of the cleaved DEF peptides were detected in chemical cross-linking experiments both in the presence and absence of 9-cis-retinoic acid. Since the purified E. coli-derived truncated hRXR alpha DEF peptide appears to fully retain its ligand binding activity, it should provide a useful model system for further structural analysis of ligand-protein interactions.
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PMID:Characterization of the ligand binding domain of human retinoid X receptor alpha expressed in Escherichia coli. 803 15

The neural cell adhesion molecule (N-CAM), is expressed in definite spatiotemporal patterns during development. To identify factors that may influence place-dependent n-cam gene expression, we have studied the binding and activation of the n-cam promoter by Pax-8, a member of the Pax family of transcription factors. Pax-8 increased n-cam promoter activity 13.4-fold in cellular co-transfection experiments, and a short segment of the promoter (-143 to -15) mediated the response. This region of the n-cam promoter produced a DNA-protein complex when incubated with either extracts from COS-7 cells transfected with the Pax-8 expression vector or a Pax-8/GST fusion protein. Pax-8 bound to the n-cam promoter through two TGCTCC motifs (designated PBS-1 and PBS-2) that resemble paired domain binding sites. Mutation of PBS-1 and PBS-2 eliminated Pax-8 activation of the n-cam promoter. Transfection of N2A neuroblastoma cells with the Pax-8 expression vector resulted in a 5-fold increase in the transcription of the endogenous n-cam gene. The combined results suggest that Pax-8 activates transcription of the n-cam gene through binding of sequences resembling paired domain binding sites in the n-cam promoter. The data raise the possibility that the n-cam promoter may be regulated by other members of the Pax gene family.
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PMID:Binding and activation of the promoter for the neural cell adhesion molecule by Pax-8. 807 51

The pGEX-2T expression vector was used to produce the ligand-binding domain from the human retinoic acid receptor alpha (hRAR alpha LBD) in Escherichia coli. The resulting fusion protein, containing the glutathione S-transferase separated from the truncated receptor (hRAR alpha 186-462) by a thrombin cleavage site, was purified with use of affinity chromatography on immobilized glutathione. A 90% homogeneity was obtained, with a specific activity of 100 pmol/mg and an overall 10% yield. Following purification and thrombin cleavage, a predominant monomeric (stokes radius = 2.3 nm, molecular mass of 32 kDa) [3H]retinoic acid hRAR alpha LBD complex was characterized by high-performance size-exclusion chromatography. The purified hRAR alpha LBD bound retinoic acid with an apparent Kd of 9 nM, a value close to the Kd of the full-length hRAR alpha expressed in COS cells. Kinetic studies at 0 degrees C demonstrate that the association of [3H]retinoic acid and [3H]CD367, a synthetic retinoid, to the overexpressed receptor was extremely rapid (complete in less than 3 min), whereas their dissociation from the receptor was slower, with half-lives of about 40 min at 0 degrees C. Experiments performed at various subzero temperatures allowed a more accurate assay of the association rate constant and indicate that the entropy of activation (delta Sa) is positive, which is characteristic of hydrophobic interactions. The ligand-binding activity was markedly decreased by pretreatment with various sulfhydryl modifying agents. 5,5'-Dithiobis(2-nitrobenzoic acid) (DTNB) appeared to be the most potent, whereas iodoacetamide was the least active. Furthermore, a series of N-alkylmaleimides was shown to inactivate the recombinant receptor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Purification and functional characterization of the ligand-binding domain from the retinoic acid receptor alpha: evidence that sulfhydryl groups are involved in ligand-receptor interactions. 824 Nov 33

To identify serum-inducible genes in the insulin-producing cell line beta TC-1, a library subtraction screening procedure was performed on serum-deprived (G0) and serum-restimulated (G1) insulin-producing beta TC-1 cells. A cDNA containing a motif with strong homology to Src homology 2 (SH2) domains was found using this procedure and called Shb. The Shb cDNA contains two methionine codons in its N-terminus and thus may code for two proteins of 67 and 56 kDa, each with one SH2 domain in its C-terminus. No other structural similarity to proteins with catalytic activity could be detected, suggesting that Shb is a so called adaptor. Shb contains the proline-rich sequence PPPGPGR between the two proposed initiator methionines which resembles a sequence for binding to Src homology 3 (SH3) domains. A second proline-rich sequence was detected after the second methionine codon. The Shb cDNA hybridized to a similar or identical mRNA of 3.1 kb expressed in mouse brain, liver, kidney, heart, NIH3T3 fibroblasts and beta TC-1 cells. Western blot analysis of the same tissues using an antiserum directed against a synthetic peptide corresponding to a part of the SH2 domain of Shb, revealed reactivity with two proteins of 56 and 67 kDa. In addition, a third reactive component of 40 kDa was detected in most tissues. Transfection and transient expression of the Shb cDNA in COS-1 cells yielded increased expression of the 67, 56 and 40 kDa proteins. Transfection and stable expression of the Shb cDNA in pig aortic endothelial cells showed increased expression primarily of the 67 kDa protein. A fusion protein consisting of the SH2 domain of Shb linked to glutathione S-transferase showed increased binding to glycoproteins of cells stimulated with platelet-derived growth factor (PDGF-BB). Furthermore, the autophosphorylated PDGF beta-receptor but not the autophosphorylated epidermal growth factor (EGF) receptor bound specifically to immobilized fusion protein. It is concluded that Shb is a novel SH2-containing protein with proline-rich domains and therefore probably involved in the signal-transduction of some ligand-activated tyrosine kinase receptors.
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PMID:Shb is a ubiquitously expressed Src homology 2 protein. 830 79


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