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:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this study, 468 Listeria strains were checked for the presence of phosphatidylinositol-specific phospholipase C (PI-PLC) activity by using a simple assay that consisted of overlaying colonies formed on agar plates with L-alpha-phosphatidylinositol as substrate. In this assay, PI-PLC-active colonies show turbid halos around the colonies as a result of the release of insoluble diacylglycerol from the substrate. This activity was detected only in the pathogenic species Listeria monocytogenes and was not present in any of the 167 strains of Listeria seeligeri, Listeria welshimeri, Listeria innocua, Listeria murrayi, and Listeria grayi tested. Hence, screening for PI-PLC activity permits discrimination between pathogenic and nonpathogenic Listeria species. In particular, the hemolytic but nonpathogenic species L. seeligeri can now be separated from the hemolytic and pathogenic species L. monocytogenes and L. ivanovii. The use of this assay will improve the specific detection and/or isolation of pathogenic Listeria species from clinical samples or food enrichment cultures.
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PMID:Phosphatidylinositol-specific phospholipase C activity as a marker to distinguish between pathogenic and nonpathogenic Listeria species. 166 37

In pancreatic islets the bulk of phosphoinositide-specific phospholipase C (PI-PLC) activity was cytosolic. The soluble enzyme was activated by submicromolar concentrations of Ca2+, independent of calmodulin. It was unaffected by glucose and a series of glycolytic intermediates, including glyceraldehyde 3-phosphate. These observations lend support to the hypothesis that glucose-stimulated inositol triphosphate production in islets may be secondary to and provoked by glucose-mediated Ca2+ influx. All four pyridine nucleotides stimulated PI-PLC. Phosphatidylinositol hydrolysis was also stimulated by dioleine and arachidonic acid, and by the polyamines, putrescine and spermine. Phosphatidylinositol hydrolysis was inhibited by chlorpromazine, tetracaine, ATP, 5'-AMP, inorganic pyrophosphate and by phosphatidylinositol 4,5-bisphosphate, phosphatidylcholine and phosphatidylserine--but not affected by phosphatidylethanolamine. The cyclic nucleotides, cAMP and cGMP had no effect on the enzyme, and GTP-gamma-S did not activate the enzyme event at very low Ca2+ concentrations. The diglyceride lipase inhibitor, RHC 80267, and the cyclooxygenase inhibitor, indomethacin, had no effect on PI-PLC activity.
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PMID:Characteristics of phosphoinositide-specific phospholipase C activity from mouse pancreatic islets. 166 77

The erbB-2 gene product, gp185erbB-2, unlike the structurally related epidermal growth factor (EGF) receptor (EGFR), exhibits constitutive kinase and transforming activity. We used a chimeric EGFR/erbB-2 expression vector to compare the mitogenic signaling pathway of the erbB-2 kinase with that of the EGFR, at similar levels of expression, in response to EGF stimulation. The EGFR/erbB-2 chimera was significantly more active in inducing DNA synthesis than the EGFR when either was expressed in NIH 3T3 cells. Analysis of biochemical pathways implicated in signal transduction by growth factor receptors indicated that both phospholipase C type gamma (PLC-gamma) and the p21ras GTPase-activating protein (GAP) are substrates for the erbB-2 kinase in NIH 3T3 fibroblasts. However, under conditions in which activation of the erbB-2 kinase induced DNA synthesis at least fivefold more efficiently than the EGFR, the levels of erbB-2- or EGFR-induced tyrosine phosphorylation of PLC-gamma and GAP were comparable. In addition, the stoichiometry of tyrosine phosphorylation of these putative substrates by erbB-2 appeared to be at least an order of magnitude lower than that induced by platelet-derived growth factor receptors at comparable levels of mitogenic potency. Thus, our results indicate that differences in tyrosine phosphorylation of PLC-gamma and GAP do not account for the differences in mitogenic activity of the erbB-2 kinase compared with either the EGFR or platelet-derived growth factor receptor in NIH 3T3 fibroblasts.
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PMID:The erbB-2 mitogenic signaling pathway: tyrosine phosphorylation of phospholipase C-gamma and GTPase-activating protein does not correlate with erbB-2 mitogenic potency. 167 40

The genomic loci of four distinct phospholipase C genes (PLC-beta, PLC-gamma I, PLC-delta and PLC-gamma II) were examined for restriction fragment length polymorphisms (RFLPs) between the genomes of three normotensive [Sprague-Dawley, Donryu and Wistar-Kyoto (WKY)] and two closely related hypertensive [spontaneously hypertensive (SHR) and SHR stroke-prone (SHR-SP)] rat strains. The RFLPs observed between SHR and WKY were classified into three types. Type I RFLPs are those observed at 4.3 kilobase (kb) and 1.9 kb by AvaI digestion for PLC-gamma probe and at 1.9 kb by AccI digestion for PLC-beta probe, where RFLP banding patterns are conserved in two hypertensive (SHR and SHR-SP) and one normotensive (Sprague-Dawley) strains. Type II RFLPs are those observed by AccI, BamHI, EcoRI and PstI digestions for PLC-beta probe, where RFLP pattern observed in SHR is shared by one normotensive (Sprague-Dawley) strain but not by SHR-SP, WKY or Donryu rats. Type III RFLPs are those detected at 6.3 kb band by Bg/II digestion for PLC-beta probe and at 1.0 kb by BamHI digestion for PLC-gamma II probe, where RFLP pattern observed in SHR is shared by two normotensive rats other than WKY. No RFLP was found for PLC-gamma I probe after testing 13 restriction enzymes. Since PLC plays a pivotal role in regulating the intracellular calcium concentration and the intracellular signal transduction, these RFLPs may offer a valuable tool for the analysis of genomic predisposition for hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Phospholipase C genes display restriction fragment length polymorphisms between the genomes of normotensive and hypertensive rats. 167 27

We have assessed the effect of somatostatin on the phospholipase C activity in isolated rat pancreatic islets. The phospholipase C activity was measured as the generation of inositol 1,4,5-trisphosphate and its metabolite inositol 1,3,4-trisphosphate from the hydrolysis of polyphosphoinositides. Inositol phosphates were measured using anion-exchange fast protein liquid chromatography analysis of extracts from islets prelabelled with myo-[3H]inositol. Somatostatin (1-1000 nmol l-1) significantly inhibited the glucose-induced (12 mmol l-1) phospholipase C activity in a concentration-dependent manner. The Ca2+ channel blocker verapamil (25 mumol l-1) also inhibited the glucose-induced (12 mmol l-1) phospholipase C, whereas the combination of somatostatin and verapamil did not induce any additional inhibition. At 3.3 mmol l-1 glucose, the hypoglycaemic sulphonylurea, tolbutamide (1 mmol l-1), increased the phospholipase C activity. This effect was reversed by somatostatin (100 nmol l-1). Tolbutamide did not further increase the glucose-induced (12 mmol l-1) phospholipase C activity. However, the somatostatin inhibition of glucose-induced (12 mmol l-1) phospholipase C was reversed by tolbutamide. The activator of adenylyl cyclase, forskolin (20 mumol l-1), did not exert any effect on the PLC-inhibition of somatostatin, whereas forskolin alone inhibited the phospholipase C activation at 12 mmol l-1 glucose. Our study demonstrates that somatostatin inhibits the hydrolysis of polyphosphoinositides in pancreatic islets, apparently via a mechanism dependent on Ca2+ and not on cAMP.
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PMID:Somatostatin inhibition of phospholipase C activity in isolated rat pancreatic islets. 168 20

We have identified the sites phosphorylated in vitro by epidermal growth factor (EGF) receptor kinase in bovine brain phospholipase C-gamma (PLC-gamma). They are tyrosine residues 472, 771, 783, and 1254. The rate of phosphorylation was fastest with the sites at 771 and 783, then at 1254, and slowest at 472. PLC-gamma isolated from cells treated with EGF is known to contain at least four tyrosine phosphate-containing peptides and two of them are identified to be residues 771 and 1254 in the accompanying paper (Wahl, M. I., Nishibe, S., Kim, J. W., Kim, H., Rhee, S. G., and Carpenter, G. (1990) J. Biol. Chem. 265, 3944-3948). The 3 residues 472, 771, and 783 are located closely to the regions of PLC-gamma which exhibit a high sequence similarity to the regulatory domain of the src family tyrosine kinases. Nevertheless, the tyrosine phosphorylation did not affect the catalytic activity of PLC-gamma in vitro. We propose, therefore, that the phosphorylation of PLC-gamma by EGF receptor kinase alters its interaction with putative inhibitory proteins and leads to its activation.
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PMID:Tyrosine residues in bovine phospholipase C-gamma phosphorylated by the epidermal growth factor receptor in vitro. 168 10

The 145-kDa phospholipase C isozyme, PLC-gamma, is an excellent substrate for the epidermal growth factor (EGF) receptor both in vivo and in vitro. We now demonstrate that EGF treatment of HSC-1 cells, a human squamous cell carcinoma-derived cell line that expresses high levels of the EGF receptor, rapidly induces tyrosine phosphorylation of two-thirds of the total cellular PLC-gamma pool. A two-step immunoaffinity protocol was used for large-scale isolation of phosphorylated PLC-gamma from the cytosol of EGF-treated HSC-1 cells. Phosphorylated PLC-gamma was digested with trypsin, then phosphotyrosine-containing peptides were purified by phosphotyrosine affinity chromatography and reverse-phase high performance liquid chromatography. The two major phosphotyrosine-containing tryptic peptides were sequenced. Comparison of the sequence data with the bovine brain PLC-gamma amino acid sequence indicated that the major, EGF-sensitive tyrosine phosphorylation sites of human PLC-gamma correspond to the bovine brain PLC-gamma tyrosine residues 771 and 1254. The former residue is adjacent to regions of PLC-gamma that contain high homology to the non-catalytic, amino-terminal region of the src tyrosine kinase. The latter residue lies near the carboxyl terminus of the PLC-gamma molecule. The accompanying manuscript (Kim J.W., Sim, S.S., Kim, U-H., Nishibe, S., Wahl, M. I., Carpenter, G., and Rhe, S. G. (1990) J. Biol. Chem. 265, 3940-3943) identifies these same 2 residues plus 2 additional tyrosine phosphorylation sites through large-scale in vitro phosphorylation of purified bovine brain PLC-gamma by the EGF receptor.
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PMID:Identification of two epidermal growth factor-sensitive tyrosine phosphorylation sites of phospholipase C-gamma in intact HSC-1 cells. 168 11

In the present study characterization of phosphatidylinositol 4,5-bisphosphate-specific phospholipase C (PIP2-PLC) activity and receptor-mediated hydrolysis of PIP2 in rat anterior pituitary membranes were investigated. Incubation of the membrane fraction of anterior pituitary homogenate with [3H]inositol-labeled PIP2 in the presence of calcium increased the concentration of the water-soluble degradation product inositol trisphosphate (IP3) in a time-dependent manner. PIP2-PLC in the rat anterior pituitary had a pH optimum at 5.5 and a requirement for cations. Ca2+ and Mg2+ could activate the enzyme. Activity was maximal at a total magnesium concentration of 1 mM and at a free Ca2+ concentration of 100 microM. The addition of the detergent Triton X-100 (0.05% w/v) to the membrane fraction resulted in a 50% decrease of PIP2-PLC activity, whereas the presence of sodium deoxycholate (1 mg/ml) in the membrane fraction increased the PIP2-PLC activity by 100%. The tachykinins substance P, 8-Tyr-substance P, physalaemin, neurokinin A, eledoisin, kassinin and neurokinin B induced receptor-mediated breakdown of [3H]inositol-labeled PIP2 in the membrane fraction in a concentration-dependent manner, but with different potencies. The tachykinins displayed the following rank order of potencies: substance P greater than 8-Tyr-substance P greater than physalaemin greater than neurokinin A greater than eledoisin greater than kassinin greater than neurokinin B, which is consistent with the involvement of a NK-1 receptor. Combined treatment of anterior pituitary membranes by substance P and thyrotropin-releasing hormone (TRH) resulted in an additional increase in PIP2-PLC activity compared to stimulation with TRH alone.
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PMID:Substance P and related tachykinins induce receptor-mediated hydrolysis of polyphosphoinositides in the rat anterior pituitary. 169 Nov 15

We investigated the interaction of phospholipase C-gamma (PLC-gamma) with wild-type and mutant forms of the platelet-derived growth factor (PDGF) beta-receptor both in vivo and in vitro. After PDGF treatment of CHO cell lines expressing wild-type or either of two mutant (delta Ki and Y825F) PDGF receptors, PLC-gamma became tyrosine phosphorylated and associated with the receptor proteins. The receptor association and tyrosine phosphorylation of PLC-gamma correlated with the ability of these receptors to mediate ligand-induced phosphatidylinositol turnover. However, both the delta Ki and Y825F mutant receptors were deficient in transmitting mitogenic signals, suggesting that the PDGF-induced tyrosine phosphorylation and receptor association of PLC-gamma are not sufficient to account for the growth-stimulatory activity of PDGF. Wild-type and delta Ki mutant PDGF receptor proteins expressed with recombinant baculovirus vectors also associated in vitro with mammalian PLC-gamma. However, baculovirus-expressed c-fms, v-fms, c-src, and Raf-1 proteins failed to associate with PLC-gamma under similar conditions. Phosphatase treatment of the baculovirus-expressed PDGF receptor greatly decreased its association with PLC-gamma. This requirement for receptor phosphorylation was also observed in vivo, where PLC-gamma could not associate with a mutant PDGF receptor (K602A) defective in autophosphorylation. PLC-gamma also coimmunoprecipitated with two other putative receptor substrates, the serine-threonine kinase Raf-1 and the 85-kilodalton phosphatidylinositol-3' kinase, presumably through its association with the ligand-activated receptor. Furthermore, baculovirus-expressed Raf-1 phosphorylated purified PLC-gamma in vitro at sites which showed increased serine phosphorylation in vivo in response to PDGF. These results suggest that PDGF directly influences PLC activity by inducing the association of PLC-gamma with a receptor signaling complex, resulting in increased tyrosine and serine phosphorylation of PLC-gamma.
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PMID:Platelet-derived growth factor (PDGF)-dependent association of phospholipase C-gamma with the PDGF receptor signaling complex. 169 40

The low affinity IgG Fc receptor, Fc gamma RIII, expressed on circulating neutrophils, natural killer (NK) cells, and tissue macrophages, is involved in effector functions such as cytotoxicity and immune complex clearance by these cells. While Fc gamma RIII is reported to be a phosphatidylinositol (PI)-linked, rather than peptide-linked, protein on neutrophils and NK cells, its membrane linkage in macrophages has not been studied. We examined the sensitivity of Fc gamma RIII to cleavage by PI-specific phospholipase C (PI-PLC) in cultured monocytes and alveolar tissue macrophages and report that this receptor is not PI-linked on these cells. We also observed normal levels of Fc gamma RIII on cultured monocytes of a patient with paroxysmal nocturnal hemoglobinuria, a disease in which PI-linked proteins are deficient. The results suggest that Fc gamma RIII occurs solely in a transmembrane form in cells of the monocyte/macrophage lineage. In addition, we studied Fc gamma RIII on a cloned NK cell line and found it to be resistant to the effects of PI-PLC under conditions that cleaved Fc gamma RIII on neutrophils. Taken together, our results provide evidence for a distinct form of Fc gamma RIII that differs from the neutrophil receptor in its structure and, possibly, in its function.
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PMID:Monocyte/macrophage Fc gamma RIII, unlike Fc gamma RIII on neutrophils, is not a phosphatidylinositol-linked protein. 169 31


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