Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have established the human nck sequence as a new oncogene. Nck encodes one SH2 and three SH3 domains, the Src homology motifs found in nonreceptor tyrosine kinases, Ras GTPase-activating protein, phosphatidylinositol 3-kinase, and phospholipase C-gamma. Overexpression of human nck in 3Y1 rat fibroblasts results in transformation as judged by alteration of cell morphology, colony formation in soft agar, and tumor formation in nude BALB/c mice. However, overexpression of nck does not induce detectable elevation of the phosphotyrosine content of specific proteins, as is observed for v-crk, another SH2/SH3-containing oncogene. Despite this fact, we demonstrate that Nck retains the ability to bind tyrosine phosphorylated proteins in vitro, using a fusion protein of Nck with glutathione-S-transferase (GST). Moreover, when incubated with lysates prepared from v-src-transformed 3Y1 cells or the nck-overexpressing cell lines, GST-Nck binds to both p60v-src and serine/threonine kinases, respectively. Although phosphotyrosine levels are not elevated in the nck-expressing fibroblasts, vanadate treatment of these cells results in a phosphotyrosine pattern that is altered from the parental 3Y1 pattern, suggestive of a perturbation of indigenous tyrosine kinase pathways. These results suggest the possibility that human nck induces transformation in 3Y1 fibroblasts by virtue of its altered affinity or specificity for the normal substrates of its rat homolog and that Nck may play a role in linking tyrosine and serine/threonine kinase pathways within the cell.
Mol Cell Biol 1992 Dec
PMID:The SH2- and SH3-containing Nck protein transforms mammalian fibroblasts in the absence of elevated phosphotyrosine levels. 128 Mar 26

Recent evidence suggests that tyrosine kinases play an important role in signal transduction mechanisms utilized by a range of different agonists in many cell types. We have investigated the effects of four different inhibitors of tyrosine kinases on IgE-dependent histamine release from human lung mast cells and basophils. Genistein inhibited the anti-IgE-induced histamine release from human basophils (at 10 microM genistein, inhibition = 55 +/- 5%, n = 17, P < 0.005) with an IC50 of 8 microM, but was much less effective in the human lung mast cell (at 10 microM, inhibition = 18 +/- 6%, n = 11, P < 0.05). Two inactive analogs of genistein, genistin and diadzein, failed to affect anti-IgE-induced histamine release significantly in either mast cells or basophils. A second inhibitor of tyrosine kinases, tyrphostin 25, inhibited IgE-dependent release from basophils (at 10 microM, inhibition = 25 +/- 7%, n = 6, P < 0.05) though it was less effective than genistein and failed to affect IgE-induced histamine release from human lung mast cells (at 10 microM, inhibition = 22 +/- 16%, n = 5, P = NS). In contrast, methyl 2,5 dihydroxycinnamate (MDC) failed to inhibit anti-IgE-dependent histamine release in human basophils (at 10 microM, inhibition = 3 +/- 3%, n = 5, P = NS) but proved to be an effective inhibitor of anti-IgE-induced degranulation in human lung mast cells (at 10 microM, inhibition = 53 +/- 16%, n = 5, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1992 Dec
PMID:Role of tyrosine kinases in IgE-mediated signal transduction in human lung mast cells and basophils. 128 Apr 50

In studies aimed at identifying and characterizing pp60c-src substrates that participate in the enhanced mitogenic response to epidermal growth factor (EGF) observed in murine C3H10T1/2 fibroblasts overexpressing c-src, we have identified a 75-kDa protein (p75) whose properties are consistent with those expected of such a substrate. We present evidence to show that p75 is immunologically related to a recently described, cytoskeleton-associated, pp60v-src substrate [Wu et al. (1991). Mol. Cell. Biol., 11, 5113-5124), and that its phosphotyrosine content is increased cooperatively by c-src overexpression and EGF stimulation. p75 is rapidly (within 2 min) phosphorylated on tyrosine upon EGF treatment and undergoes a second, prolonged phase of tyrosyl phosphorylation from 7 to 21 h after EGF addition, suggesting that tyrosyl phosphorylation of p75 is important for late as well as early events following EGF receptor activation. Enhanced tyrosyl phosphorylation of p75 is also seen when cells overexpressing c-src are treated with platelet-derived growth factor (PDGF), but significantly less phosphorylation is observed with insulin and fibroblast growth factor (FGF). Both basal and EGF-induced tyrosyl phosphorylation of p75 are reduced in cells overexpressing mutated forms of c-src (unmyristylated, or kinase deficient) as compared with wild-type c-src overexpressers, indicating the dependence of the enhanced tyrosyl phosphorylation on membrane-associated, enzymatically active pp60c-src. In cellular fractionation experiments p75 partitions with the cytosol, while immunofluorescence studies reveal a striking colocalization with pp60c-src at the plasma membrane and in the perinuclear region. Partial co-staining of p75 and actin occurs at the cell's periphery. These data provide evidence for p75 being a direct substrate of pp60c-src. The possible role of p75 in the enhanced response to EGF seen in c-src overexpressers is discussed.
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PMID:Identification and characterization of a cytoskeleton-associated, epidermal growth factor sensitive pp60c-src substrate. 128 4

The cytoplasmic domain of the cloned erythropoietin (EPO) receptor (EPOR) contains no protein kinase motif, yet addition of EPO to EPO-responsive cells causes an increase in protein-tyrosine phosphorylation. Here we show that addition of EPO or interleukin-3 (IL-3) to an IL-3-dependent cell line expressing the wild-type EPOR causes a small fraction (less than 5%) of total cellular EPOR to shift in gel mobility from 66 to 72 kDa, due at least in part to phosphorylation. Using biotinylated EPO as an affinity reagent, we show that the 72-kDa species is greatly enriched on the cell surface. To demonstrate that a protein kinase activity associates with cell surface EPOR, cells were incubated with biotinylated EPO and then cross-linked with a thiol-cleavable chemical cross-linker. The avidin-agarose-selected complexes were incubated with [gamma-32P]ATP. After in vitro phosphorylation and denaturation without reducing agent, both antiphosphotyrosine and anti-EPOR antibodies immunoprecipitated labeled 72-kDa EPOR and an unidentified 130-kDa phosphoprotein (pp130), indicating that a protein kinase is associated with cell surface EPOR and that a fraction of the EPOR was phosphorylated on tyrosine residues either in the cells or during the cell-free phosphorylation reaction. Under reducing conditions, the 72-kDa phosphorylated EPOR but not pp130 was immunoprecipitated with an anti-EPOR antibody, suggesting that the pp130 is bound to the EPOR by the thiol-cleavable chemical cross-linker. Previously, we showed that deletion of the 42 carboxy-terminal amino acids of the EPOR allows cells to grow in 1/10 the normal EPO concentration, without affecting receptor number or affinity. Two carboxy-terminal truncated EPO receptors that are hyperresponsive to EPO were poorly phosphorylated during the in vitro reaction, suggesting that the carboxy-terminal region of the EPOR contains a site for phosphorylation or a site for interaction with a protein kinase. Our data suggests that phosphorylation or interaction with a protein kinase in the carboxy-terminal region may down-modulate the proliferative action of the EPOR.
Mol Cell Biol 1992 Feb
PMID:In vitro phosphorylation of the erythropoietin receptor and an associated protein, pp130. 131 Jan 50

Phenylketonuria (PKU) is a metabolic disorder secondary to a deficiency of the hepatic enzyme phenylalanine hydroxylase (PAH). The recent creation of a mouse strain for PAH deficiency has provided an excellent model system to explore the possibility of its phenotypic correction by hepatic gene therapy. A recombinant retrovirus containing the mouse PAH cDNA under the transcriptional control of the human CMV promoter was constructed and used to transduce hepatocytes isolated from PAH-deficient mice. Viral-transduced hepatocytes produced dramatically higher levels of mouse PAH mRNA as compared to control mock-infected hepatocytes. The PAH mRNA was translated efficiently into PAH protein that is capable of converting phenylalanine to tyrosine in vitro. These results demonstrate that the PAH-deficient mouse hepatocytes can be readily reconstituted by retroviral-mediated gene transduction, which is a crucial step towards somatic gene therapy for PKU.
Somat Cell Mol Genet 1992 Jan
PMID:Reconstitution of enzymatic activity in hepatocytes of phenylalanine hydroxylase-deficient mice. 131 61

To determine how the human cdc25 gene product acts to regulate p34cdc2 at the G2 to M transition, we have overproduced the full-length protein (cdc25Hs) as well as several deletion mutants in bacteria as glutathione-S-transferase fusion proteins. The wild-type cdc25Hs gene product was synthesized as an 80-kDa fusion protein (p80GST-cdc25) and was judged to be functional by several criteria: recombinant p80GST-cdc25 induced meiotic maturation of Xenopus oocytes in the presence of cycloheximide; p80GST-cdc25 activated histone H1 kinase activity upon addition to extracts prepared from Xenopus oocytes; p80GST-cdc25 activated p34cdc2/cyclin B complexes (prematuration promoting factor) in immune complex kinase assays performed in vitro; p80GST-cdc25 stimulated the tyrosine dephosphorylation of p34cdc2/cyclin complexes isolated from Xenopus oocyte extracts as well as from overproducing insect cells; and p80GST-cdc25 hydrolyzed p-nitrophenylphosphate. In addition, deletion analysis defined a functional domain residing within the carboxy-terminus of the cdc25Hs protein. Taken together, these results suggest that the cdc25Hs protein is itself a phosphatase and that it may function directly in the tyrosine dephosphorylation and activation of p34cdc2 at the G2 to M transition.
Mol Biol Cell 1992 Jan
PMID:cdc25+ encodes a protein phosphatase that dephosphorylates p34cdc2. 131 80

The cytochrome c oxidase subunit I (COI) gene sequences from planarian (Dugesia japonica) DNA, most probably of mitochondrial origin, are heterogeneous. Taking advantage of the heterogeneity that occurs primarily in silent sites of the COI DNA sequences, amino acid assignments of several codons have been deduced as nonuniversal: UGA = Trp, AAA = Asp, and AGR (R: A or G) = Ser. In addition, UAA, a stop codon in the universal genetic code, is tentatively assumed to be a tyrosine codon, because three of the sequences examined have UAA at the well-conserved tyrosine site of UAY (Y: U or C) in other planarian sequences as well as in the mitochondria of human, Xenopus, sea urchin, Drosophila, Trypanosoma, and Saccharomyces cerevisiae. AUA would most probably be an isoleucine codon in these mitochondria, whereas it is a methionine codon in the majority of nonplant mitochondria.
J Mol Evol 1992 Apr
PMID:Planarian mitochondria. II. The unique genetic code as deduced from cytochrome c oxidase subunit I gene sequences. 131 9

p42/microtubule-associated protein kinase (p42mapk) is activated by tyrosine and threonine phosphorylation, and its regulatory phosphorylation is likely to be important in signalling pathways involved in growth control, secretion, and differentiation. Here we show that treatment of quiescent 3T3 cells with diverse agonists results in the appearance of an activity capable of causing the in vitro phosphorylation of p42mapk on the regulatory tyrosine and to a lesser extent on the regulatory threonine, resulting in enzymatic activation of the p42mapk. This p42mapk-activating activity is capable of phosphorylating a kinase-defective p42mapk mutant, thus confirming its activity as a kinase.
Mol Cell Biol 1992 May
PMID:Growth factor-induced activation of a kinase activity which causes regulatory phosphorylation of p42/microtubule-associated protein kinase. 131 51

Two antipeptide antibodies, one against the peptide corresponding to residues 307-327 (alpha Y91) and one against the peptide corresponding to the C-terminal portion (alpha C92) of the deduced amino acid sequence of the extracellular signal-regulated kinase 1 (ERK1), precipitated two 41-kDa and/or two 43-kDa phospho-proteins from mitogen-stimulated Swiss 3T3 cells. Electrophoretic mobilities on two-dimensional gels of the immunoprecipitated 41- and 43-kDa phosphoproteins were similar to those of the 41- and 43-kDa cytosol proteins, whose increased tyrosine phosphorylation we and others had originally identified in various mitogen-stimulated cells (Cooper, J. A., Sefton, B. M., and Hunter, T. (1984) Mol. Cell. Biol. 4, 30-37; Kohno, M. (1985) J. Biol. Chem. 260, 1771-1779); phosphopeptide map analysis revealed that they were respectively identical molecules. All those phosphoproteins contained phosphotyrosine, and the more acidic forms contained additional phosphothreonine. Immunoprecipitated 41- and 43-kDa phosphoproteins had serine/threonine kinase activity toward myelin basic protein (MBP) and microtuble-associated protein 2 (MAP2). With the combination of two-dimensional gel electrophoresis and the kinase assay in MBP-containing polyacrylamide gels of the alpha Y91 immunoprecipitates, with or without phosphatase 2A treatment, we showed that only their acidic forms were active. These results clearly indicate that 41- and 43-kDa proteins, the increased tyrosine phosphorylation of which is rapidly and commonly induced by mitogen stimulation of fibroblasts, are family members of ERKs/MAP2 kinases and that phosphorylation both on tyrosine and threonine residues is necessary for their activation.
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PMID:Mitogen-induced tyrosine-phosphorylated 41- and 43-kDa proteins are family members of extracellular signal-regulated kinases/microtubule-associated protein 2 kinases. 131 74

In this paper an immunodominant epitope of Topoisomerase I is described. An epitope expression sublibrary was constructed from Topoisomerase I cDNA. The subclones were screened with an antiserum from a patient with systemic sclerosis (SSc). The positive clones defined one immunodominant B cell epitope (epitope III), which was located at the carboxyterminal part of the protein. The epitope, 52 amino acids in length, neither contains the p30gag sequence nor the suggested active site Tyr-723, both presumed antibody recognition sites. More than 70% of our anti-TopoI sera recognize this epitope III, indicating that it is a major recognition site of the anti-TopoI autoantibodies in SSc sera. DNA relaxation experiments show that all sera that recognize epitope III and most sera with antibodies to other epitopes inhibit Topoisomerase I activity.
Mol Biol Rep 1992 May
PMID:Analysis of an immunodominant epitope of topoisomerase I in patients with systemic sclerosis. 131 98


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