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)

To investigate the difference in signaling between insulin and insulin-like growth factor I (IGF-I), we studied the effects of these hormones on the phosphorylation state of Crk-associated substrate (Cas) in cells expressing human insulin receptor (HIRc). In the basal state, Cas was heavily tyrosine-phosphorylated, and insulin dephosphorylated Cas in a time- and dose-dependent manner. On the other hand, IGF-I phosphorylated rather than dephosphorylated Cas in HIRc cells. In HIRY/F2 cells expressing a mutant insulin receptor lacking a binding site of SHP-2, a protein-tyrosine phosphatase containing src homology 2 (SH2) regions, insulin accelerated phosphorylation of Cas, as did IGF-I. In HIRc cells expressing a mutant SHP-2 lacking a PTPase domain (DeltaPTP), which interfered with SHP-2 function, insulin failed to dephosphorylate Cas. In whole cell lysate obtained in the basal state, Cas bound to a glutathione-S transferase fusion protein containing SH2 domains of SHP-2 and dissociated from this GST protein in response to insulin. These results indicate that the opposite regulation of Cas phosphorylation by insulin and IGF-I may be mediated through different properties of their receptors, and that the interaction of the insulin receptor with SHP-2 may play an important role in determining the tyrosine-phosphorylation state of Cas.
...
PMID:Opposite regulation of tyrosine-phosphorylation of p130(Cas) by insulin and insulin-like growth factor I. 983 15

Crk is a member of a family of adapter proteins predominantly composed of Src homology 2 and 3 domains, whose role in signaling pathways is presently unclear. Using an in situ electroporation system which permits the introduction of glutathione S-transferase (GST) fusion proteins into cells, we found that c-CrkII bound to p130(cas), but not to paxillin in serum-starved rat-1 fibroblasts overexpressing the human insulin receptor (HIRc cells) in vivo. 17 nM insulin stimulation dissociated the binding of c-CrkII to p130(cas), whereas 13 nM insulin-like growth factor-I, 16 nM epidermal growth factor (EGF), and 10% serum each showed little or no effect. We found that stress fiber formation is consistent with a change in the p130(cas).c-CrkII interactions before and after growth factor stimulation. Microinjection of either GST-Crk-SH2 or -Crk-(N)SH3 domains, or anti-Crk antibody each inhibited stress fiber formation before and after insulin-like growth factor-I, EGF, and serum stimulation. Insulin stimulation by itself caused stress fiber breakdown and there was no additive effect of microinjection. Microinjection of anti-p130(cas) antibody also blocked stress fiber formation in quiescent cells. Microinjection of the Crk-inhibitory reagents also inhibited DNA synthesis after insulin-like growth factor-I, EGF, and serum stimulation, but not after insulin. These data suggest that the complex containing p130(cas).c-CrkII may play a crucial role in actin cytoskeleton organization and in anchorage-dependent DNA synthesis.
...
PMID:The functional role of CrkII in actin cytoskeleton organization and mitogenesis. 991 38

Insulin receptor substrate (IRS) proteins play a crucial role as signaling molecules in insulin action. Serine phosphorylation of IRS proteins has been hypothesized as a cause of attenuating insulin signaling. The current study investigated serine kinase activity toward IRS-1 in several models of insulin resistance. An in vitro kinase assay was developed that used partially purified cell lysates as a kinase and glutathione S-transferase fusion proteins that contained various of IRS-1 fragments as substrates. Elevated serine kinase activity was detected in Chinese hamster ovary/insulin receptor (IR)/IRS-1 cells and 3T3-L1 adipocytes chronically treated with insulin, and in liver and muscle of obese JCR:LA-cp rats. It phosphorylated the 526-859 amino acid region of IRS-1, whereas phosphorylation of the 2-516 and 900-1235 amino acid regions was not altered. Phosphopeptide mapping of the 526-859 region of IRS-1 showed three major phosphopeptides (P1, P2, and P3) with different patterns of phosphorylation depending on the source of serine kinase activity. P1 and P2 were strongly phosphorylated when the kinase activity was prepared from insulin-resistant Chinese hamster ovary/IR/IRS-1 cells, weakly phosphorylated by the kinase activity from insulin-resistant 3T3-L1 adipocytes, and barely phosphorylated when the extract was derived from insulin-resistant liver. In contrast, P3 was phosphorylated by the serine kinase activity prepared from all insulin-resistant cells and tissues of animals. P1 and P2 phosphorylation can be explained by mitogen-activated protein kinase activity based on the phosphopeptide map generated by recombinant ERK2. In contrast, mitogen-activated protein kinase failed to phosphorylate the P3 peptide, suggesting that another serine kinase regulates this modification of IRS-1 in insulin-resistant state.
...
PMID:Identification of enhanced serine kinase activity in insulin resistance. 1018 59

To examine the molecular mechanism of insulin receptor trafficking, we investigated the intracellular signaling molecules that regulate this process in Rat1 fibroblasts overexpressing insulin receptors. Cellular localization of insulin receptors was assessed by confocal laser microscopy with indirect immunofluorescence staining. Insulin receptors were visualized diffusely in the basal state. Insulin treatment induced the change of insulin receptor localization to perinuclear compartment. This insulin-induced insulin receptor trafficking was not affected by treatment of the cells with PI3-kinase inhibitor (wortmannin), whereas treatment with MEK [mitogen-activated protein (MAP) kinase-Erk kinase] inhibitor (PD98059) partly inhibited the process in a dose-dependent manner. Interestingly, treatment with both wortmannin and PD98059 almost completely inhibited insulin receptor trafficking. The functional importance of PI3-kinase and MAP kinase in the trafficking process was directly assessed by using single cell microinjection analysis. Microinjection of p85-SH2 and/or catalytically inactive MAP kinase ([K71A]Erk1) GST fusion protein gave the same results as treatment with wortmannin and PD98059. Furthermore, to determine the crucial step for the requirement of PI3-kinase and MAP kinase pathways, the effect of wortmannin and PD98059 on insulin receptor endocytosis was studied. Insulin internalization from the plasma membrane and subsequent insulin degradation were not affected by treatment with wortmannin and PD98059. In contrast, insulin receptor down-regulation from the cell surface and insulin receptor degradation, after prolonged incubation with insulin, were markedly impaired by the treatment. These results suggest that PI3-kinase and MAP kinase pathways synergistically regulate insulin receptor trafficking at a step subsequent to the receptor internalization.
...
PMID:Synergistic role of the phosphatidylinositol 3-kinase and mitogen-activated protein kinase cascade in the regulation of insulin receptor trafficking. 1043 44

Hematopoietic cell growth, differentiation, and commitment to a restricted lineage are guided by a set of cytokines acting exclusively on cells expressing the corresponding cytokine receptor. The macrophage colony stimulating factor (M-CSF, also termed CSF-1) and its cognate receptor, the tyrosine kinase c-Fms, are essential for monocyte and macrophage development. The underlying molecular mechanism, however, is poorly understood. Here we identified a novel Fms-interacting protein (FMIP, MW 78 kDa) which binds transiently via its N-terminal 144 residues to the cytoplasmic domain of activated Fms-molecules. Binding of FMIP was paralleled by rapid tyrosine phosphorylation within the binding domain which drastically reduced its ability to associate with Fms. Binding was specific as evidenced by co-immunoprecipitation and association with recombinant GST-Fms fusion proteins. No binding was observed with the tyrosine phosphorylated cytoplasmic domains of c-Kit, TrkA, c-Met, and the insulin receptor. The role of FMIP in hematopoietic differentiation was studied in the bipotential myeloid progenitor cell line, FDC-P1Mac11. Overexpression of FMIP prevented M-CSF induced macrophage differentiation. Instead, cells differentiated into granulocytes. Our data suggest that the level of FMIP expression could form a threshold that decides about differentiation either into macrophages or into granulocytes.
...
PMID:FMIP, a novel Fms-interacting protein, affects granulocyte/macrophage differentiation. 1059 51

The molecular adapter Grb7 is likely to be implicated in the development of certain cancer types. In this study we show that Grb7 binds the insulin receptors, when they are activated and tyrosine phosphorylated. This interaction is documented by two-hybrid experiments, GST pull-down assays and in vivo coimmunoprecipitations. In addition, our results argue in favor of a preferential association between Grb7 and the insulin receptors when compared to other tyrosine kinase receptors like the EGF receptor, the FGF receptor and Ret. Interestingly, Grb7 is not a substrate of the insulin receptor tyrosine kinase activity. Grb7 binds the activated tyrosine kinase loop of the insulin receptors. Two domains of Grb7 are implicated in the insulin receptor binding: the SH2 domain and the PIR (phosphotyrosine interacting region). The role of these two domains in the interaction with the insulin receptor was already reported for Grb10 and Grb14, the other members of the Grb7 family of proteins. However, the relative importance of these domains varies, considering the receptor and the Grb protein. These differences should be a determinant of the specificity of the receptor tyrosine kinase-Grbs binding, and thus of the implication of Grb7/10/14 in signal transduction.
...
PMID:Evidence for an interaction between the insulin receptor and Grb7. A role for two of its binding domains, PIR and SH2. 1080 66

SOCS proteins are a class of proteins that are negative regulators of cytokine receptor signaling via the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. In a yeast two-hybrid screen of a human fetal brain library, we have previously identified SOCS-2 as a binding partner of the activated IGF-I receptor (IGFIR). To test whether or not SOCS-3 also binds to the IGFIR, we cloned human SOCS-3 by reverse transcription-polymerase chain reaction from human skeletal muscle mRNA. SOCS-3 mRNA was expressed in many human fetal and adult tissues and in some human cancer cell lines (Hela, A549 pulmonary adenocarcinoma and G361 human melanoma). We found that human SOCS-3 protein interacts directly with the cytoplasmic domains of the activated IGFIR and the insulin receptor (IR) in the yeast two-hybrid assay. In GST-SOCS-3 pull-down experiments using IGFIR from mammalian cells and in immunoprecipitation experiments in which IGFIR and FLAG-SOCS-3 were transiently expressed in human embryonic kidney 293 cells, we found that SOCS-3 interacts constitutively with IGFIR in vitro and in intact cells. Unlike SOCS-2, hSOCS-3 was phosphorylated on tyrosines in response to IGF-I addition to 293 cells. We conclude that SOCS-3 binds to the IGFIR and may be a direct substrate for the receptor tyrosine kinase.
...
PMID:Suppressor of cytokine signaling (SOCS)-3 protein interacts with the insulin-like growth factor-I receptor. 1107 52

A recently reported new member of the Vav family proteins, Vav3 has been identified as a Ros receptor protein tyrosine kinase (RPTK) interacting protein by yeast two-hybrid screening. Northern analysis shows that Vav3 has a broad tissue expression profile that is distinct from those of Vav and Vav2. Two species of Vav3 transcripts, 3.4 and 5.4 kb, were detected with a differential expression pattern in various tissues. Transient expression of Vav in 293T and NIH 3T3 cells demonstrated that ligand stimulation of several RPTKs (epidermal growth factor receptor [EGFR], Ros, insulin receptor [IR], and insulin-like growth factor I receptor [IGFR]) led to tyrosine phosphorylation of Vav3 and its association with the receptors as well as their downstream signaling molecules, including Shc, Grb2, phospholipase C (PLC-gamma), and phosphatidylinositol 3 kinase. In vitro binding assays using glutathione S-transferase-fusion polypeptides containing the GTPase-binding domains of Rok-alpha, Pak, or Ack revealed that overexpression of Vav3 in NIH 3T3 cells resulted in the activation of Rac-1 and Cdc42 whereas a deletion mutant lacking the N-terminal calponin homology and acidic region domains activated RhoA and Rac-1 but lost the ability to activate Cdc42. Vav3 induced marked membrane ruffles and microspikes in NIH 3T3 cells, while the N-terminal truncation mutants of Vav3 significantly enhanced membrane ruffle formation but had a reduced ability to induce microspikes. Activation of IR further enhanced the ability of Vav3 to induce membrane ruffles, but IGFR activation specifically promoted Vav3-mediated microspike formation. N-terminal truncation of Vav3 activated its transforming potential, as measured by focus-formation assays. We conclude that Vav3 mediates RPTK signaling and regulates GTPase activity, its native and mutant forms are able to modulate cell morphology, and it has the potential to induce cell transformation.
...
PMID:Vav3 mediates receptor protein tyrosine kinase signaling, regulates GTPase activity, modulates cell morphology, and induces cell transformation. 1109 73

Protein tyrosine phosphatases are a class of enzymes that function to modulate tyrosine phosphorylation of cellular proteins and play an essential role in regulating cell function. PTP1B has been implicated in the negative regulation of the insulin signaling pathway by dephosphorylating the activated insulin receptor. Inhibiting this phosphatase and preventing the insulin-receptor downregulation has been suggested as a target for the treatment of Type II diabetes. A high-throughput screen for inhibitors of PTP1B was developed using a scintillation proximity assay (SPA) with GST-- or FLAG--PTP1B((1-320)) and a potent [(3)H]-tripeptide inhibitor. The problem of interference from extraneous oxidizing and alkylating agents which react with the cysteine active-site nucleophile was overcome by the use of the catalytically inactive C215S form of the native enzyme (GST--PTP1B(C215S)). The GST--PTP1B was linked to the protein A scintillation bead via GST antibody. The radiolabeled inhibitor when bound to the enzyme gave a radioactive signal that was competed away by the unknown competitive compounds. Further utility of PTP1B(C215S) was demonstrated by mixing in the same well both the catalytically inactive GST--PTP1B(C215S) and the catalytically active FLAG--CD45 with an inhibitor. Both a binding and kinetic assay was then performed in the same 96-well plate with the inhibition results determined for the PTP1B(C215S) (binding assay) and CD45 (activity assay). In this way inhibitors could be differentiated between the two phosphatases under identical assay conditions in one 96-well assay plate. The use of a mutant to reduce interference in a binding assay and compare with activity assays is also amenable for most cysteine active-site proteases.
...
PMID:Development of a robust scintillation proximity assay for protein tyrosine phosphatase 1B using the catalytically inactive (C215S) mutant. 1140 1

CEACAM1, a tumor suppressor (previously known as pp120), is a plasma membrane protein that undergoes phosphorylation on Tyr(488) in its cytoplasmic tail by the insulin receptor tyrosine kinase. Co-expression of CEACAM1 with insulin receptors decreased cell growth in response to insulin. Co-immunoprecipitation experiments in intact NIH 3T3 cells and glutathione S-transferase pull-down assays revealed that phosphorylated Tyr(488) in CEACAM1 binds to the SH2 domain of Shc, another substrate of the insulin receptor. Overexpressing Shc SH2 domain relieved endogenous Shc from binding to CEACAM1 and restored MAP kinase activity, growth of cells in response to insulin, and their colonization in soft agar. Thus, by binding to Shc, CEACAM1 sequesters this major coupler of Grb2 to the insulin receptor and down-regulates the Ras/MAP kinase mitogenesis pathway. Additionally, CEACAM1 binding to Shc enhances its ability to compete with IRS-1 for phosphorylation by the insulin receptor. This leads to a decrease in IRS-1 binding to phosphoinositide 3'-kinase and to the down-regulation of the phosphoinositide 3'-kinase/Akt pathway that mediates cell proliferation and survival. Thus, binding to Shc appears to constitute a major mechanism for the down-regulatory effect of CEACAM1 on cell proliferation.
...
PMID:Shc and CEACAM1 interact to regulate the mitogenic action of insulin. 1169 16


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

---