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)

1. In rat parotid acini, vanadate affects amylase secretion and intracellular messengers according to its concentration. 2. Low concentrations (in the micromolar range) concentrations of vanadate stimulate amylase secretion and potentiate the secretory effect of carbamylcholine, but inhibit the amylase release in response to isoproterenol. 3. Vanadate increases inositol phosphates (mono-, bis- and trisphosphate) and potentiate the stimulatory effect of carbachol on inositol bis- and trisphosphate. 4. Vanadate also decreases the intracellular cyclic AMP concentration and the increase in response to isoproterenol or forskolin. 5. High concentrations (in the millimolar range) of vanadate inhibit the increase in inositol phosphate induced by carbachol. 6. It is concluded that low concentrations of vanadate activate regulatory proteins coupled to phospholipase C and adenylate cyclase while high concentrations of vanadate inhibit inositol bisphosphatase.
Gen Pharmacol 1993 Mar
PMID:Interaction of vanadate with isolated rat parotid acini. 768 3

The effects of nonelectrolytes on conductivity and viscosity of KCl solutions as well as on ion channel conductance were studied. Mobility of ions in solutions were found to solely depend on percent concentration (w/w) of the nonelectrolytes added and to be effectively independent on their chemical nature (sugars or polyglycols) and molecular size. Proportional changes in both the ion channel conductance and the conductivity of bulk solution induced by low m. w. nonelectrolytes may be used as a criterion of diffusion mechanism of ion transport through channels. The slope of the dependence of ion channel conductance on conductivity of bulk solution containing different concentrations of nonelectrolytes is a good measure of channel permeability for nonelectrolyte. A new method of pore size determination is introduced. Results of practical application of this simple method to three types of ion channels (formed by alpha-latrotoxin, staphylococcal alpha-toxin and its N-terminal fragment) are shown. The advantages and disadvantages of the method are discussed.
Gen Physiol Biophys 1993 Apr
PMID:Relation between ionic channel conductance and conductivity of media containing different nonelectrolytes. A novel method of pore size determination. 769 79

The gene for phosphatidylinositol-specific phospholipase C (PI-PLC) of Listeria monocytogenes has been cloned and shown to be expressed in Escherichia coli cells from own as well as from the lactose gene promoter. The recombinant plasmid has been constructed on the basis of pRIT2T vector and carries the hybrid gone. 3-end of which is a fragment of protein A gene of Staphylococcus aureus. 3-end is a gene for phospholipase plcA, both in the same reading frame. The resultant construction is shown to code in Escherichia coli cells for the hybrid recombinant protein A:Pl-PLC. Purified preparation of the hybrid protein and polyclonal rabbit antiserum to it were obtained. The obtained antiserum to the hybrid protein containing phospholipase as en C-end domain has been shown to react specifically to phospholipase in Escherichia coli recombinant strain harbouring the constructed recombinant plasmid as well as the one in the culture fluid of listeria.
Mol Gen Mikrobiol Virusol
PMID:[Cloning and expression of the phosphatidylinositol-specific phospholipase C gene from Listeria monocytogenes]. 773 95

The PLC1 gene of the yeast Saccharomyces cerevisiae has been discovered to encode a homolog of mammalian phosphoinositide-specific phospholipase C (PLC). Five temperature-sensitive plc1 mutants were isolated by in vitro mutagenesis with subsequent plasmid shuffling. All of the amino acid substitutions that caused a temperature-sensitive growth phenotype were located in the X or the Y region, both of which are conserved among PLC isoenzymes. The PLC activity of all products of mutant plc1 genes was dramatically lower than that of the wild-type product, indicating that PLC activity itself is important for cell growth. At the restrictive temperature, plc1 mutant cells ceased growth at random times during the cell cycle, a result that suggests that PLC1 is required at several or all stages of the cell cycle.
Mol Gen Genet 1995 Apr 20
PMID:Isolation and characterization of temperature-sensitive plc1 mutants of the yeast Saccharomyces cerevisiae. 775 23

1. RBL-2H3 cells permeabilized with alpha-toxin responded to dinitrophenol (30-40 mol/mol)-conjugated human serum albumin, as antigen, to secrete [14C]serotonin in the micromolar range of free Ca2+. 2. Calcium ion alone did not cause substantial secretion. 3. Guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) (100 microM) in combination with Ca2+ produced only negligible [14C]serotonin secretion. 4. GTP gamma S, in the presence of cytochalasin D, caused optimal secretion of [14C]serotonin in a Ca(2+)-dependent manner.
Gen Pharmacol 1994 Jul
PMID:Fc epsilon RI-stimulated Ca(2+)-dependent secretion from rat basophilic leukemia (RBL-2H3) cells permeabilized with Staphylococcal alpha-toxin: Fc epsilon RI-operated signals are not mimicked by the actions of GTP gamma S. 795 35

We evaluated the effects of two protein kinase C (PKC) inhibitors, staurosporine (ST) and H-7, on LH-activated phospholipase C and adenylate cyclase activity by measuring the production of inositol phosphates (IP) and cAMP in freshly dispersed granulosa cells from mature preovulatory follicles of laying hens. ST and H-7 dose-dependently potentiated LH-stimulated IP generation, whereas a protein kinase A (PKA) inhibitor (H-8) had no effect. The PKC activator, phorbol ester TPA (50 nM), significantly inhibited LH-stimulated IP production, which was completely prevented by ST. Both ST and H-7, while having no effect on basal cAMP levels, significantly and dose-dependently potentiated LH-stimulated, but not forskolin-stimulated cAMP production. However, progesterone production in response to LH, forskolin, and 8-Br-cAMP was inhibited in granulosa cells preincubated for 30 min with H-7 or ST. H-7 and ST had no effect on 25-hydroxycholesterol- and pregnenolone-supported progesterone production. These results support a negative feedback role for PKC in LH-initiated signal transduction in avian granulosa cells. PKC blockade removes the inhibitory effect on LH-stimulated phospholipase C and adenylate cyclase activity. The inhibitory effect of H-7 and ST on progesterone synthesis could be attributed to inhibition of PKA and/or steps proximal to cholesterol side-chain cleavage.
Gen Comp Endocrinol 1994 Mar
PMID:Signal transduction in avian granulosa cells: effects of protein kinase C inhibitors. 819 46

The effects of acetylcholine (ACh) and histamine (His) on the membrane potential and current were examined in JR-1 cells, a mucin-producing epithelial cell line derived from human gastric signet ring cell carcinoma. The tight-seal, whole cell clamp technique was used. The resting membrane potential, the input resistance, and the capacitance of the cells were approximately -12 mV, 1.4 G ohms, and 50 pF, respectively. Under the voltage-clamp condition, no voltage-dependent currents were evoked. ACh or His added to the bathing solution hyperpolarized the membrane by activating a time- and voltage-independent K+ current. The ACh-induced hyperpolarization and K+ current persisted, while the His response desensitized quickly (< 1 min). These effects of ACh and His were mediated predominantly by m3-muscarinic and H1-His receptors, respectively. The K+ current induced by ACh and His was inhibited by charybdotoxin, suggesting that it is a Ca(2+)-activated K+ channel current (IK.Ca). The measurement of intracellular Ca2+ ([Ca2+]i) using Indo-1 revealed that both agents increased [Ca2+]i with similar time courses as they increased IK.Ca. When EGTA in the pipette solution was increased from 0.15 to 10 mM, the induction of IK.Ca by ACh and His was abolished. Thus, both ACh and His activate IK.Ca by increasing [Ca2+]i in JR-1 cells. In the Ca(2+)-free bathing solution (0.15 mM EGTA in the pipette), ACh evoked IK.Ca transiently. Addition of Ca2+ (1.8 mM) to the bath immediately restored the sustained IK.Ca. These results suggest that the ACh response is due to at least two different mechanisms; i.e., the Ca2+ release-related initial transient activation and the Ca2+ influx-related sustained activation of IK.Ca. Probably because of desensitization, the Ca2+ influx-related component of the His response could not be identified. Intracellularly applied inositol 1,4,5-trisphosphate (IP3), with and without inositol 1,3,4,5-tetrakisphosphate (IP4), mimicked the ACh response. IP4 alone did not affect the membrane current. Under the steady effect of IP3 or IP3 plus IP4, neither ACh nor His further evoked IK.Ca. Intracellular application of heparin or of the monoclonal antibody against the IP3 receptor, mAb18A10, inhibited the ACh and His responses in a concentration-dependent fashion. Neomycin, a phospholipase C (PLC) inhibitor, also inhibited the agonist-induced response in a concentration-dependent fashion. Although neither pertussis toxin (PTX) nor N-ethylmaleimide affected the ACh or His activation of IK,Ca, GDP beta S attenuated and GTP gamma S enhanced the agonist response.(ABSTRACT TRUNCATED AT 400 WORDS)
J Gen Physiol 1993 Oct
PMID:Activation of Ca(2+)-dependent K+ current by acetylcholine and histamine in a human gastric epithelial cell line. 827 Sep 9

Heparin is thought to inhibit InsP3 binding to receptors involved in the intracellular release of Ca2+. Injection of heparin into Limulus ventral photoreceptors to high intracellular concentrations reduces the amplitude and slows the rate of rise of voltage-clamp currents induced by brief flashes, tends to make the responses to long flashes more "square," and tends to block the light-induced rise in [Ca2+]i detected by arsenazo III. In these ways, intracellular heparin mimics the effects of high concentrations of intracellular BAPTA or EGTA. In addition, the effects of heparin are attenuated by prior injection of BAPTA to high intracellular concentrations. Neomycin and spermine are thought to inhibit phospholipase C activity. Injections of spermine or neomycin to low intracellular concentrations largely mimic the effects of intracellular heparin. These findings suggest that the predominant effect of polyamines is to inhibit light-induced production of InsP3 by phospholipase C activity and thereby reduce the light-induced increase in [Ca2+]i. Our findings suggest that excitation can proceed in the absence of InsP3-induced increases in [Ca2+]i, but (a) the gain and speed of transduction are reduced and (b) adaptation is largely blocked.
J Gen Physiol 1993 Jun
PMID:Intracellular injection of heparin and polyamines. Effects on phototransduction in limulus ventral photoreceptors. 833 23

Infection of human cells with poliovirus leads to modification of phospholipase activity. Phospholipase C, which generates inositol triphosphate, is stimulated, whereas the activation of phospholipase A2 by the calcium ionophore A23187 is inhibited. Analysis of phospholipid moieties in media of HeLa cells infected with poliovirus indicates that the release of fatty acids is not enhanced during infection, suggesting that phospholipase A1 and A2 activities are not stimulated. The release of choline into the medium is significantly higher 3 h after infection, indicating that a phospholipase that has phosphatidylcholine as its substrate becomes activated. This activation requires viral gene expression because inhibitors of poliovirus gene expression added at the beginning of infection block choline release, but continuous viral protein synthesis is not required. Choline and phosphorylcholine are released into the medium, but the pools of both are gradually depleted in poliovirus-infected cells, perhaps as a consequence of their release into the medium and the increased synthesis of phospholipids that takes place in poliovirus-infected cells. Inhibitors of phospholipase activity such as mepacrine, zinc or cadmium ions significantly reduce this increased release of choline from poliovirus-infected cells. Labelling of cells with [3H]phosphatidylcholine suggests that the choline released from infected cells comes, at least in part, from the hydrolysis of this compound. These results indicate that, in addition to the activation of the phospholipase C which hydrolyses phosphatidylinositol in poliovirus-infected cells, a phospholipase C that acts on a phosphatidylcholine is also activated.
J Gen Virol 1993 Jun
PMID:Enhancement of phospholipase activity during poliovirus infection. 838 98

1. ATP exerts multiple receptor-mediated effects on isolated hepatocytes: glycogenolysis through the activation of glycogen phosphorylase (cAMP-independent, IP3/calcium-mediated), inactivation of glycogen synthase, inhibition of the glucagon effect on cAMP, activation of phospholipase D. The fact that some of these effects can be selectively altered and that they are not, or differently, reproduced by some other analogues of ATP, suggests the presence of more than one receptor. (i) Pertussis toxin abolishes the anti-glucagon effect of ATP without affecting its glycogenolytic effect. (ii) Single cell calcium measurements reveal major differences between ATP and ADP, (iii) 2MeSATP and ADP beta S, in clear contrast to ATP, barely increase the levels of IP3 and their glycogenolytic effects is completely blocked by phorbol ester treatment of hepatocytes. (iv) 2MeSATP differs from ADP beta S since it has no anti-glucagon effect. 2. Effects of UTP on isolated hepatocytes so far do not show any difference with effects of ATP, suggesting interaction with the same receptor(s). 3. It is proposed that liver plasma membranes contain (at least) three different receptors mediating (a) the activation of phospholipase C, (b) the activation of phospholipase D and (c) the inhibition of adenylate cyclase.
Gen Pharmacol 1993 Mar
PMID:The complex interaction of ATP and UTP with isolated hepatocytes. How many receptors? 848 12


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