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:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The neu/HER-2 proto-oncogene (also called erbB-2) encodes a transmembrane glycoprotein related to the epidermal growth factor receptor. We have purified to homogeneity a 44 kd glycoprotein from the medium of ras-transformed cells that stimulates phosphorylation of the Neu protein and retains activity after elution from the polyacrylamide gel. The protein is active at picomolar concentrations and displays a novel N-terminal sequence. Cross-linking experiments with radiolabeled p44 result in specific labeling of Neu, indicating that p44 is a ligand for Neu or a related receptor. The purified protein induces phenotypic differentiation of cultured human breast cancer cells, including altered morphology and synthesis of milk components. This is accompanied by an increase in nuclear area, inhibition of cell growth (probably by cell cycle arrest at the late S or the G2/M phases), and induction of DNA polyploidy. We propose the name Neu differentiation factor (NDF) for p44.
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PMID:Isolation of the neu/HER-2 stimulatory ligand: a 44 kd glycoprotein that induces differentiation of mammary tumor cells. 134 15

Activation of mature CD4+ T lymphocytes by antigen-presenting cells involves engagement of the CD3/T-cell antigen receptor complex along with the CD4 surface glycoprotein and the phosphorylation of cellular proteins on tyrosine residues leading to stimulation of a variety of cellular second-messenger systems. Several recent studies have implicated non-receptor protein tyrosine kinase of the src family, especially p56lck and p59fyn, in mediating at least a portion of these tyrosine phosphorylation events. In the present study we have examined the involvement of one type of second-messenger system, phosphatidylinositol-3 kinase (PI-3 kinase), in signal transduction during antibody-induced activation of normal resting human CD4+ T cells. We demonstrate that PI-3 kinase activity is increased following co-approximation of CD4 with the T-cell receptor and that PI-3 kinase activity co-precipitates with the CD4-p56lck complex. We also show that following T-cell activation a complex containing PI-3 kinase activity can be demonstrated in CD3 epsilon immunoprecipitates which is distinct from that which interacts with p56lck.
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PMID:Identification of distinct populations of PI-3 kinase activity following T-cell activation. 137 84

The majority of infants born to HIV-positive mothers are not infected in utero, suggesting that the pregnancy factors produced by fetal trophoblasts may provide protection against HIV-1 infection. Except for steroid female hormones, little is known of other pregnancy factors that may regulate either resistance or susceptibility to HIV-1. Human chorionic gonadotropin (hCG)--the major glycoprotein produced by the placental trophoblast throughout the pregnancy--was tested on reverse transcriptase activity in HIV-infected ACH-2 lymphocytes and U1 monocytes. The results suggest that low non-cytotoxic doses of hCG (0.01-1.0 IU range) may inhibit viral replication in maternal blood cells.
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PMID:Effect of human chorionic gonadotropin (hCG) on reverse transcriptase activity in HIV-1 infected lymphocytes and monocytes. 138 34

Previously, we have shown that nuclear envelope assembly in cell-free extracts of Xenopus eggs requires two distinct vesicle-containing fractions, called Nuclear Envelope Precursor Fractions A and B (NEP-A and NEP-B). These fractions are characterized further in this paper and the manner in which they are regulated during metaphase is examined. Antisera against the NEP-B fraction recognized several proteins common to NEP-B and Xenopus oocyte or liver nuclei, but not to NEP-A or cytosol. A known glycoprotein component of the nuclear pore complex, p62, also co-fractionated with NEP-B, whereas the Xenopus egg lamin LIII did not. Together, these results provide further evidence that the NEP-B fraction contains precursors of the nuclear envelope. The regulation of NEP-A and -B function during metaphase, when the nuclear envelope is disassembled, was examined by treating each fraction with metaphase cytosol or purified protein kinase preparations isolated from metaphase-arrested eggs. Treatment of NEP-B with metaphase cytosol, under conditions where proteins are irreversibly phosphorylated, inhibited the subsequent assembly of the nuclear envelope by preventing the binding of NEP-B to chromatin. In contrast, similar treatment of NEP-A did not affect its ability to form nuclear envelopes. The changes in NEP-B during metaphase did not appear to be regulated directly by either p34cdc2/cyclin B, S6 kinase II or MAP kinase.
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PMID:Regulation of nuclear envelope precursor functions during cell division. 140 Jun 33

Platelet-derived growth factor (PDGF) is a cationic glycoprotein of approximately 30 kDa, composed of two subunits. These subunit chains are termed A (18 kDa) and B (12-14 kDa) with high homology of the peptide sequences, including 8 cysteine residues at identical positions. Three isoforms of PDGF, AA, BB homodimers and AB heterodimer are distributed in the different tissues and cell lines suggesting that these isoforms have different functions. Two types of PDGF receptors alpha, and beta with Mr of 160-180 kDa are seen on the cell surface. PDGFR alpha can bind to both A and B subunits of the PDGD, while PDGFR beta, only B subunit. PDGF (AA) combines alpha alpha, PDGF (AB) makes dimers of alpha alpha and alpha beta, and PDGF (BB) can make three types of dimers, alpha alpha, alpha beta, and beta beta. These dimeric PDGFRs are active forms and phosphorylate its own domain and other neighbor specific proteins. The substrates of the receptor kinase are phospholipase C-gamma, GTPase activating protein (GAP), serine/threonine kinase Raf-1 and others. These molecules are thought to transfer information of the PDGFs on its receptors to the nucleus.
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PMID:[Function, molecular structure and gene expression regulation of Platelet-derived growth factor]. 143 82

We investigated the glycoconjugates of the human bronchial glands at light and electron microscopic level by means of lectin histochemistry in combination with neuraminidase digestion and beta-elimination reaction. Both direct and indirect techniques using lectin-peroxidase, lectin-gold, and glycoprotein-gold complexes were applied. The binding pattern of the six lectins (ConA, HPA, DSA, WGA, LEA, and PNA) used in the present study suggests that mucous and serous cells of human bronchial glands contain both N- and O-glycosylated proteins in the secretory granules. Asparagine-linked oligosaccharides containing Gal(beta-1,4) GlcNAc and Man residues were abundant in serous cells. The demonstration of both the terminal Neu 5Ac (alpha-2,3, or 6) Gal (beta-1,4) GlcNAc sequence in the N-linked oligosaccharides of mucous cells and the terminal disaccharide Gal (beta-1,4) GlcNAc in the N-linked oligosaccharide chains of serous cells suggests the existence of complex type sugar chains N-glycosidically linked to the peptide region of the glycoproteins. The binding pattern of the DSA and the neuraminidase-DSA sequence provides evidence for the existence of sialyltransferase activity in the forming mucous granules of mucous bronchial cells.
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PMID:Ultrastructural localization of glycoconjugates in human bronchial glands: the subcellular organization of N- and O-linked oligosaccharide chains. 155 69

The neu protooncogene (also called HER2 and c-erbB2) encodes a cell-surface tyrosine kinase structurally related to the receptor for the epidermal growth factor (EGF). We have previously reported that a candidate ligand for the neu receptor is secreted by ras-transformed fibroblasts. Biochemical analyses of the neu stimulatory activity indicate that the ligand is a 35-kDa glycoprotein that is heat stable but sensitive to reduction. The factor is precipitable by either high salt concentrations or acidic alcohol. Partial purification of the molecule by selective precipitation, heparin-agarose chromatography, and gel filtration in dilute acid resulted in an active ligand, which is capable of stimulating the protooncogenic receptor but is ineffective on the oncogenic neu protein, which is constitutively active. The purified fraction, however, retained the ability to stimulate also the related receptor for EGF, suggesting that these two receptors are functionally coupled through a bidirectional mechanism. Alternatively, the presumed ligand interacts simultaneously with both receptors. The presented biochemical characteristics of the factor are expected to enable a completely purified factor with which to explore these possibilities.
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PMID:Biochemical analysis of the ligand for the neu oncogenic receptor. 167 25

In order to study the antigenicity of envelope 46 kDa glycoprotein (gp46) of human T-cell leukemia virus type-I (HTLV-1), we have generated monoclonal anti-gp46 antibodies (MAbs), REY-7, REY-11, REY-16, REY-30, MET-2 and MET-3 from rats and mice. Immunoblot and immunofluorescence assays showed that these MAbs recognize gp46 and its related antigens, and specifically stained HTLV-I-bearing cells. All MAbs reacted with a recombinant gp46 antigen, N147, expressing the 147 amino acids in the C-terminal half of gp46. By using various synthetic peptides corresponding to the gp46 sequence, epitopes recognized by REY-7 and MET-3, REY-11 and REY-16, and REY-30 were mapped to regions corresponding to the amino acids 175-199, 253-282 and 288-312, respectively. MET-2 did not react with any of the peptides used. These results indicate that the present MABs are directed against at least 4 distinct epitopes expressed on the C-terminal half of gp46. The binding of these MAbs to gp46 was specifically inhibited by sera from HTLV-I-infected individuals, but none of these MAbs inhibited the cell fusion activity of HTLV-I.
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PMID:Generation and characterization of monoclonal antibodies against multiple epitopes on the C-terminal half of envelope gp46 of human T-cell leukemia virus type-I (HTLV-I). 169 31

Three T cell clones derived from rabies virus-immunized BALB/c mice were analysed for specificity and function. The clones proved to be broadly cross-reactive by responding to different rabies virus isolates (PM, ERA, CVS, HEP) and other representatives of the genus Lyssavirus, like the Duvenhage-6 (DUV6) and Mokola (MOK) viruses. The clones detected three different epitopes: an epitope expressed on the matrix protein (M) shared by PM, HEP, MOK and DUV6 viruses (clone AA8), an epitope expressed on the M-protein shared by PM, ERA, CVS, HEP and MOK viruses (clone 35A) and finally an epitope expressed on the glycoprotein (G-protein) shared by PM, ERA, CVS, HEP and MOK viruses (clone BG2). Antigen recognition of all clones proved to be MHC-restricted and they all displayed the CD4+ CD8- phenotype. Intravenous inoculation of the T cells in syngeneic mice, which had been injected intracutaneously in the ear with HEP virus, resulted in a localized DTH reaction characteristic for TH1 cells. In vitro, the clones were able to provide help to rabies virus-primed B cells, resulting in the production of virus-specific antibodies directed against all the four structural proteins of rabies virus. Further analysis of this antibody response revealed that part of it was directed against antigenic determinants of the G-protein which induce virus neutralizing antibody.
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PMID:Rabies virus cross-reactive murine T cell clones: analysis of helper and delayed-type hypersensitivity function. 196 28

The human homolog of the rat neu oncogene, HER2 (also termed c-erbB2) has been demonstrated in amplified form in human breast tumors with poor prognosis. Although amplification of the gene correlates with expression of a 185-kDa transmembrane glycoprotein, no extensive information is available regarding the extent of tissue and tumor specificity of this gene product. We have addressed this issue by immunohistochemically evaluating the expression of p185 HER2 in normal tissue and various tumors using monoclonal antibodies (MAbs) to distinct epitopes of its extracellular domain. No detectable levels of p185 HER2 were found in fetal tissues analyzed, with the exception of renal tubules in 2 out of 3 specimens tested and in intestinal epithelium. In adult tissues, detectable levels of this glycoprotein were found in a restricted number of cell types, the expression being heterogeneous among individuals and cell histotypes. Among the neoplasms assayed p185 HER2 was expressed in 46% of primary breast cancers, in 28% of ovarian tumors and in 30% of colon rectum malignancies. No male breast adenocarcinomas were p185-positive. A large number of other tumors tested revealed only a low incidence of expression of the p185. In metastatic breast tumors p185 HER2 was demonstrated homogeneously among multiple autologous lesions and almost invariably (80%) the expression of p185 in the primary lesion correlated with that of the deriving metastases. Our findings indicate that the expression of the p185 HER2 represents a tumor marker of clinical relevance in breast cancer. Whether this holds true for other malignancies remains to be explored.
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PMID:Expression of the p185 encoded by HER2 oncogene in normal and transformed human tissues. 196 37


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