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 function of the Xenopus c-mos proto-oncogene product (Mos(xe)) has been investigated during oocyte maturation. Experiments with a new antibody able to immunoblot Mos(xe) demonstrated the time course of MAP kinase (MAP K) activation in oocytes paralleled Mos(xe) accumulation, and in activated eggs the deactivation of MAP K paralleled the degradation of Mos(xe). Ablation of Mos synthesis by microinjection of antisense oligodeoxynucleotides abolished activation of MAP K by progesterone, but microinjection of GST-Mos fully restored both MAP K activation and germinal vesicle breakdown (GVBD). The Mos(xe) level at metaphase of Meiosis I (MI) was 2 - 3-fold less than that at metaphase of Meiosis II (MII), but MAP K activation was maximal at metaphase in both MI and MII. In the transition between MI and MII, both cyclin B and Mos(xe) levels rapidly declined in the presence of cycloheximide and injection of exogenous GST-Mos(xe) did not prevent degradation of either protein, although MAP K was activated. Microinjection of GST-Mos(xe) into oocytes was able to activate MAP K before GVBD and H1 kinase activation, and microinjection of constitutively-activated thiophosphorylated MAP K induced de novo synthesis of Mos(xe) before H1 kinase activation, suggesting the existence of a positive feedback loop between MAP K and Mos(xe) accumulation.
...
PMID:Mos proto-oncogene function during oocyte maturation in Xenopus. 866 47

MAP kinase-activated protein (MAPKAP) kinase-2 is activated in vivo by reactivating kinase (RK), a MAP kinase (MAPK) homologue stimulated by cytokines and cellular stresses. Here we show that in vitro RK phosphorylates human GST-MAPKAP kinase-2 at Thr25 in the proline-rich N-terminal region Thr222 and Ser272 in the catalytic domain and Thr334 in the C-terminal domain. Using novel methodology we demonstrate that activation of MAPKAP kinase-2 requires the phosphorylation of any two of the three residues Thr222, Ser272 and Thr334. Ser9, Thr25, Thr222, Ser272, Thr334 and Thr338 became 32P-labelled in stressed KB cells and labelling was prevented by the specific RK inhibitor SB 203580, establishing that RK phosphorylates Thr25, Thr222, Ser272 and Thr334 in vivo. The 32P-labelling of Thr338 is likely to result from autophosphorylation. GST-MAPKAP kinase-2 lacking the N-terminal domain was inactive, but activated fully when phosphorylated at Thr222, Ser272 and Thr334 by p42 MAPK or RK. In contrast, full-length GST-MAPKAP kinase-2 was phosphorylated at Thr25 (and not activated) by p42 MAPK, suggesting a role for the N-terminal domain in specifying activation by RK in vivo. The mutant Asp222/Asp334 was 20% as active as phosphorylated MAPKAP kinase-2, and this constitutively active form may be useful for studying its physiological roles.
...
PMID:Identification of novel phosphorylation sites required for activation of MAPKAP kinase-2. 884 84

Haploid cells of budding yeast Saccharomyces cerevisiae respond to mating pheromones by inducing genes required for conjugation, arresting cell cycle progression, and undergoing morphological changes. The same cells respond to nutrient deprivation by altering budding pattern and inducing genes required for invasive growth. Both developmental alternatives to vegetative proliferation require the MAP kinase Kss1 and the transcriptional transactivator Ste12. Using a two-hybrid screen for gene products that interact with Kss1, two homologous and previously uncharacterized loci (DIG1 and DIG2, for down-regulator of invasive growth) were identified. DIG2 is pheromone-inducible, whereas DIG1 is constitutively expressed. Dig1 colocalizes with Kssl in the nucleus, coimmunoprecipitates with Kss1 from cell extracts in a pheromone-independent manner, and is phosphorylated by Kss1 in immune complexes in a pheromone-stimulated manner. Kss1 binds specifically to a GST-Dig1 fusion in the absence of any other yeast protein. Using the two-hybrid method, both Dig1 and Dig2 also interact with the other MAP kinase of the pheromone response pathway, Fus3. However, neither dig1 or dig2 single mutants, nor a dig1 dig2 double mutant, have a discernible effect on mating. In contrast, dig1 dig2 cells constitutively invade agar medium, whereas a dig1 dig2 ste12 triple mutant does not, indicating that Dig1 and Dig2 share a role in negatively regulating the invasive growth pathway. High-level expression of Dig1 suppresses invasive growth and also causes cells to appear more resistant to pheromone-imposed cell cycle arrest. Ste12 also binds specifically to GST-Dig1 in the absence of any other yeast protein. Collectively, these findings indicate that Dig1, and most likely Dig2, are physiological substrates of Kssl and suggest that they regulate Ste12 function by direct protein-protein interaction.
...
PMID:Two novel targets of the MAP kinase Kss1 are negative regulators of invasive growth in the yeast Saccharomyces cerevisiae. 891 85

Many fungal pathogens invade plants using specialized infection structures called appressoria that differentiate from the tips of fungal hyphae contacting the plant surface. We demonstrate a role for a MAP kinase that is essential for appressorium formation and infectious growth in Magnaporthe grisea, the fungal pathogen responsible for rice blast disease. The PMK1 gene of M. grisea is homologous to the Saccharomyces cerevisiae MAP kinases FUS3/KSS1, and a GST-Pmk1 fusion protein has kinase activity in vitro. pmk1 mutants of M. grisea fail to form appressoria and fail to grow invasively in rice plants. pmk1 mutants are still responsive to cAMP for early stages of appressorium formation, which suggests Pmk1 acts downstream of a cAMP signal for infection structure formation. PMK1 is nonessential for vegetative growth and sexual and asexual reproduction in culture. Surprisingly, when expressed behind the GAL1 promoter in yeast, PMK1 can rescue the mating defect in a fus3 kss1 double mutant. These results demonstrate that PMK1 is part of a highly conserved MAP kinase signal transduction pathway that acts cooperatively with a cAMP signaling pathway for fungal pathogenesis.
...
PMID:MAP kinase and cAMP signaling regulate infection structure formation and pathogenic growth in the rice blast fungus Magnaporthe grisea. 894 11

STE20-homologous proteins have been implicated in mammalian MAP kinase pathways as important transducers of signals from p21 family GTPases. We have cloned a novel STE20 family member, which we call KHS for kinase homologous to SPS1/STE20, that encodes a kinase of 95 kD which is expressed in a variety of tissues. Transiently expressed fusion protein GST-KHS exhibits phosphotransferase activity toward a panel of test substrates, including myelin basic protein (MBP), which is phosphorylated by all known STE20 homologues. KHS is most closely related to another human STE20, GC kinase (74% similar in the catalytic domain), which has recently been placed upstream of the stress-activated MAP kinases (SAPKs/JNKs). KHS also activates JNK in transient coexpression experiments, suggesting a role for KHS in the stress response of fibroblasts. Characterization and comparison of the regulation of these two kinases will be important in elucidating MAP kinase signalling cascades.
...
PMID:A novel human SPS1/STE20 homologue, KHS, activates Jun N-terminal kinase. 903 72

Monoclonal antibody MPM-2 recognizes a large family of mitotic phosphoproteins in a phosphorylation-dependent manner. The antigenic phosphoepitope, designated the MPM-2 epitope, putatively consists of hydrophobic residue-Thr/Ser-Pro-hydrophobic residue-uncharged/basic residue. In this study, we addressed whether this sequence motif contains all the information necessary for recognition and phosphorylation by the kinase that phosphorylates most MPM-2 antigens. A fusion protein between glutathione S-transferase and a 19-residue peptide that contained two representative MPM-2 epitope sequences overlapping with two potential MAP kinase phosphorylation sites was constructed. Both the MPM-2 epitope sequences in the fusion protein (GST-MPM2) were phosphorylated by Xenopus egg extract, making the fusion protein MPM-2 reactive. However, while MAP kinase phosphorylated both the MPM-2 epitope sequences, neither ME kinase-H, a good candidate for a major MPM-2 epitope kinase, nor mitotic cdc2 kinase, which is known to phosphorylate certain MPM-2 antigens in vitro, phosphorylated GST-MPM2 to any significant extent. Furthermore, depletion of MAP kinase activity removed most, if not all, of the GST-MPM2 phosphorylating activity from crude Xenopus egg extracts. These results suggest that additional or different structural information than that provided by the deduced MPM-2 epitope sequence is required for recognition and phosphorylation by ME kinase-H or other major MPM-2 epitope kinases. They also offer a valid explanation for selective phosphorylation of certain MPM-2 antigens by MAP kinase as well as selective recognition of certain phosphorylated MAP kinase substrates by MPM-2.
...
PMID:MPM-2 epitope sequence is not sufficient for recognition and phosphorylation by ME kinase-H. 930 47

We have studied the phosphorylation of the Bcl-2 family of proteins by different mitogen-activated protein (MAP) kinases. Purified Bcl-2 was found to be phosphorylated by the c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) p54-SAPKbeta, and this is specific insofar as the extracellular signal-regulated kinase 1 (ERK1) and p38/RK/CSBP (p38) catalyzed only weak modification. Bcl-2 undergoes similar phosphorylation in COS-7 when coexpressed together with p54-SAPKbeta and the constitutive Rac1 mutant G12V. This is seen by both 32PO4 labeling and the appearance of five discrete Bcl-2 bands with reduced gel mobility. As anticipated, both intracellular p54-SAPKbeta activation and Bcl-2 phosphorylation are blocked by co-transfection with the MAP kinase specific phosphatase MKP3/PYST1. MAP kinase specificity is also seen in COS-7 cells as Bcl-2 undergoes only weak phosphorylation when co-expressed with enzymatically activated ERK1 or p38. Four critical residues undergoing phosphorylation in COS-7 cells were identified by expression of the quadruple Bcl-2 point mutant T56A,S70A,T74A, S87A. Sequencing phosphopeptides derived from tryptic digests of Bcl-2 indicates that purified GST-p54-SAPKbeta phosphorylates identical sites in vitro. This is the first report of Bcl-2 phosphorylation by the JNK/SAPK class of MAP kinases and could indicate a key modification allowing control of Bcl-2 function by cell surface receptors, Rho family GTPases, and/or cellular stresses.
...
PMID:Bcl-2 undergoes phosphorylation by c-Jun N-terminal kinase/stress-activated protein kinases in the presence of the constitutively active GTP-binding protein Rac1. 931 39

Nef is a membrane-associated cytoplasmic phosphoprotein that is well conserved among the different human (HIV-1 and HIV-2) and simian immunodeficiency viruses and has important roles in down-regulating the CD4 receptor and modulating T-cell signaling pathways. The ability to modulate T-cell signaling pathways suggests that Nef may physically interact with T-cell signaling proteins. In order to identify Nef binding proteins and map their site(s) of interaction, we targeted a highly conserved acidic sequence at the carboxyl-terminal region of Nef sharing striking similarity with an acidic sequence at the c-Raf1-binding site within the Ras effector region. Here, we used deletion and site-specific mutagenesis to generate mutant Nef proteins fused to bacterial glutathione S-transferase in in vitro precipitation assays and immunoblot analysis to map the specific interaction between the HIV-1LAI Nef and c-Raf1 to a conserved acidic sequence motif containing the core sequence Asp-Asp-X-X-X-Glu (position 174-179). Significantly, we demonstrate that substitution of the nonpolar glycine residue for either or both of the conserved negatively charged aspartic acid residues at positions 174 and 175 in the full-length recombinant Nef protein background completely abrogated binding of c-Raf1 in vitro. In addition, lysates from a permanent CEM T-cell line constitutively expressing the native HIV-1 Nef protein was used to coimmunoprecipitate a stable Nef-c-Raf1 complex, suggesting that molecular interactions between Nef and c-Raf1, an important downstream transducer of cell signaling through the c-Raf1-MAP kinase pathway, occur in vivo. This interaction may account for the Nef-induced perturbations of T-cell signaling and activation pathways in vitro and in vivo.
...
PMID:Binding of c-Raf1 kinase to a conserved acidic sequence within the carboxyl-terminal region of the HIV-1 Nef protein. 962 70

At fertilization, sea urchin eggs undergo a series of activation events, including a Ca2+ action potential, Ca2+ release from the endoplasmic reticulum, an increase in intracellular pH, sperm pronuclear formation, MAP kinase dephosphorylation, and DNA synthesis. To examine which of these events might be initiated by activation of phospholipase Cgamma (PLCgamma), which produces the second messengers inositol trisphosphate (IP3) and diacylglycerol, we used recombinant SH2 domains of PLCgamma as specific inhibitors. Sea urchin eggs were co-injected with a GST fusion protein composed of the two tandem SH2 domains of bovine PLCgamma and (1) Ca2+ green dextran to monitor intracellular free Ca2+, (2) BCECF dextran to monitor intracellular pH, (3) Oregon Green dUTP to monitor DNA synthesis, or (4) fluorescein 70-kDa dextran to monitor nuclear envelope formation. Microinjection of the tandem SH2 domains of PLCgamma produced a concentration-dependent inhibition of Ca2+ release and also inhibited cortical granule exocytosis, cytoplasmic alkalinization, MAP kinase dephosphorylation, DNA synthesis, and cleavage after fertilization. However, the Ca2+ action potential, sperm entry, and sperm pronuclear formation were not prevented by injection of the PLCgammaSH2 domain protein. Microinjection of a control protein, the tandem SH2 domains of the phosphatase SHP2, had no effect on Ca2+ release, cortical granule exocytosis, DNA synthesis, or cleavage. Specificity of the inhibitory action of the PLCgammaSH2 domains was further indicated by the finding that microinjection of PLCgammaSH2 domains that had been point mutated at a critical arginine did not inhibit Ca release at fertilization. Additionally, Ca2+ release in response to microinjection of IP3, cholera toxin, cADP ribose, or cGMP was not inhibited by the PLCgammaSH2 fusion protein. These results indicate that PLCgamma plays a key role in several fertilization events in sea urchin eggs, including Ca2+ release and DNA synthesis, but that the action potential, sperm entry, and male pronuclear formation can occur in the absence of PLCgamma activation or Ca2+ increase.
...
PMID:Identification of PLCgamma-dependent and -independent events during fertilization of sea urchin eggs. 998 35

Lysophosphatidic acid (LPA) is the prototypic G-protein-coupled receptor agonist that activates the Ras-mitogen-activated protein (MAP) kinase cascade through pertussis toxin (PTX)-sensitive Gi and enhanced tyrosine kinase activity. We recently detected a 100 kDa protein (p100) that binds to the C-terminal SH3 domain of growth-factor-receptor-bound protein 2 (Grb2) and becomes tyrosine phosphorylated in a PTX-sensitive manner in LPA-treated Rat-1 cells [Kranenburg, Verlaan, Hordijk and Moolenaar (1997) EMBO J. 16, 3097-3105]. Through glutathione S-transferase-Grb2 affinity purification and microsequencing, we have now identified p100 as dynamin-II, a GTPase that regulates clathrin-mediated endocytosis. We show that in Rat-1 cells, Grb2-bound dynamin-II is rapidly tyrosine phosphorylated in response to LPA in a PTX-sensitive manner. Thus, tyrosine phosphorylation of Grb2-bound dynamin-II may be a critical event in Gi-mediated activation of the Ras-MAP kinase cascade in fibroblasts.
...
PMID:Gi-mediated tyrosine phosphorylation of Grb2 (growth-factor-receptor-bound protein 2)-bound dynamin-II by lysophosphatidic acid. 1008 21


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

---