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)

All strains of Legionella pneumophila tested produced detectable levels of extracellular protease, phosphatase, lipase, deoxyribonuclease, ribonuclease, and beta-lactamase activity. Weak starch hydrolysis was also demonstrated for all strains. Elastase, collagenase, phospholipase C, hyaluronidase, chondroitinase, neuraminidase, or coagulase were not detected in any of these laboratory-maintained strains.
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PMID:Extracellular enzymes of Legionella pneumophila. 626 49

An extracellular bactericidal substance was isolated from the supernatant of Streptococcus mutans Rm-10 culture fluid and partially purified with 60% ammonium sulfate precipitation, differential centrifugation, and gel filtration on Sephadex G-200. There was a good correlation of the sensitivity profiles of indicator strains whether assayed on solid medium or with purified material from cell-free culture fluid, indicating that the same inhibitory substance is produced on solid medium and in broth. Vapor from organic solvents such as chloroform, acetone, ethanol, and ether as well as heat treatment at 100 degrees C for 30 min had little effect on the bactericidal factor. It was sensitive to trypsin and pronase and resistant to deoxyribonuclease, ribonuclease, lysozyme, and phospholipase C. The inhibitor was not infective, and electron microscopic studies failed to reveal phage or phage-like particles in concentrated solutions of the bactericidal material. The results indicate that the extracellular bactericidal substance is indeed a bacteriocin. Activity in broth cultures reached a maximum only after exponential growth had ceased. It was active against other streptococcal strains as well as strains of Actinomyces naeslundii, A. viscosus, Bacillus subtilis and Staphylococcus aureus, but not against strains of Fusobacterium nucleatum and Escherichia coli.
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PMID:Isolation, partial purification and preliminary characterization of a bacteriocin from Streptococcus mutans Rm-10. 641 23

The ability of dolichyl-P-P-oligosaccharide:peptide oligosaccharyltransferase to use exogenous substrates (a previously labeled oligosaccharide lipid and an Asn-X-Thr containing heptapeptide) is shown to require phospholipid. The enzyme was extracted from porcine thyroid rough microsomes using NaCl-Nonidet P-40. When measured at low concentration, in a neutral detergent-containing medium, it undergoes a rapid loss of activity, which renders impossible quantitative estimates in the range of 0-50 micrograms microsomal protein/50 microliters assay. We observed that inactivation could be prevented by supplementing the assay with a previously heat-treated suspension of microsomes in neutral detergent, or with the corresponding extract. Further investigation revealed that phospholipids are responsible for this enzyme stabilization, since phospholipase A2 and phospholipase C treatments were both able to abolish this effect. When individual phospholipids were compared for their protective efficiency, egg yolk phosphatidylcholine was found to be by far the most efficient. Phosphatidylglycerol, phosphatidylinositol and phosphatidylserine were only slightly effective, while phosphatidylethanolamine and lysophosphatidylcholine had no effect at all. Of those tested, partly unsaturated phosphatidylcholines with 16-18 carbon atom acyl chains were the most active, at an optimal concentration of 1-2 mM. Under these conditions a Km of 15 microM was measured for the acceptor, a synthetic ribonuclease heptapeptide, and a Km of 0.55 microM for the donor, dolichyl-P-P-GlcNAc2-Man9-Glc2-3. These findings were confirmed by subjecting a sodium deoxycholate extract to depletion of endogenous lipids by gel filtration. Enzyme activity was totally abolished and then restored (up to now only partially) by addition of phosphatidylcholine.
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PMID:Phosphatidylcholine requirement for the N-glycosylation of synthetic peptides by detergent-solubilized oligosaccharyltransferase. 654 Jan 20

By using a suckling mouse assay, heat-stable enterotoxin (ST) was purified from the culture filtrate of Yersinia enterocolitica isolated from a diarrheal patient. The purification procedures involve ultrafiltration with an Amicon HIP-10 hollow fiber, ethanol fractionation, protamine sulfate treatment, diethylaminoethyl-Sephacel and hydroxylapatite column chromatographies, and Sephacryl S-200 superfine gel filtration. About 408-fold purification was achieved, with a yield of 12.0%. The minimal effective dose of purified ST was about 110 ng in the suckling mouse assay. The molecular weight of purified ST was 9,000 by Sephadex G-100 superfine gel filtration. The purified ST was stable to heating (100 degrees C for 20 min, 121 degrees C for 20 min) and did not lose its toxicity after treatment with protease, trypsin, lipase, phospholipase C, ribonuclease, deoxyribonuclease, beta-glucosidase, and neuraminidase. The purified ST was separated by isoelectric focusing into two active fractions, with pI's of 3.29 (ST-1) and 3.00 (ST-2), respectively. Antiserum from guinea pigs immunized with the purified ST neutralized the activity of both Y. enterocolitica ST and Escherichia coli ST.
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PMID:Partial purification and characterization of heat-stable enterotoxin produced by Yersinia enterocolitica. 721 60

In retinal pigment epithelium, apically applied epinephrine changes the conductance of specific ions which subsequently affects the membrane voltage and stimulates transepithelial fluid transport. In this investigation, myo-[3H]inositol radiotracer studies, radioligand binding with [125I]HEAT, and ribonuclease protection assays were performed to examine the coupling of this receptor to phosphoinositide hydrolysis and the specific mRNA subtypes expressed in cultured human retinal pigment epithelial cells. After labeling second to sixth passage cells with 3-muCi myo-[3H]inositol for 24 hr, epinephrine caused a dose- and time-dependent increase in [3H]inositol phosphate products (EC50 of 0.7 microM). This stimulation was antagonized by prazosin but not by propranolol. The effect of epinephrine was potentiated by the presence of the monoamine oxidase inhibitor, pargyline (10 microM). Pertussis toxin (1 microgram per well) attenuated the stimulatory effect of epinephrine. In the radioligand binding assays, [125I]HEAT binding sites varied among different cell lines, with a range of 44 to 200 fmol (mg protein)-1. Using a ribonuclease protection assay, alpha 1D and alpha 1B, but not alpha 1C, adrenergic mRNA subtypes were detected in cultured human cells. Collectively, these results show that the catecholamines act on a potentially heterogeneous population of alpha 1-adrenergic receptors coupled to phospholipase C by a pertussis toxin-sensitive G protein.
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PMID:Binding, coupling, and mRNA subtype heterogeneity of alpha 1-adrenergic receptors in cultured human RPE. 761 18

5-HT1a receptors in the hippocampus play a critical role in modulating limbic system output. The activity and level of 5-HT1a receptors are modulated by glucocorticoid levels. The present study was undertaken to test the hypothesis that glucocorticoids attenuate the transcriptional activity of the 5-HT1a receptor gene. Using in situ hybridization and RNase protection assays, we observed a substantial increase in 5-HT1a mRNA expression after adrenalectomy in the same hippocampal regions in which 5-HT1a binding sites are increased. This increase in 5-HT1a mRNA expression occurs as early as 1 h after adrenalectomy and precedes the increase in receptor binding sites. Further in situ hybridization analysis showed that 5-HT1a mRNA is increased within individual hippocampal cells after adrenalectomy. Administration of dexamethasone completely prevents the adrenalectomy-induced elevation in hippocampal 5-HT1a receptor mRNA. Nuclear run-on assays showed that the rate of transcription of 5-HT1a mRNA after adrenalectomy increased 70% above the rate from control preparations and could be reduced to basal levels by the administration of dexamethasone. Adrenalectomy did not cause an increase in functional coupling of 5-HT1a receptors to adenylyl cyclase or phospholipase C. These results suggest that transcription of hippocampal 5-HT1a receptor mRNA is under negative regulation by corticosteroid hormones.
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PMID:Transcriptional regulation of hippocampal 5-HT1a receptors by corticosteroid hormones. 776 98

In an attempt to isolate new G protein-coupled receptors from turkey erythrocytes, reverse transcribed polymerase chain reaction was performed on fetal turkey blood RNA using degenerate primers based on conserved sequences present in seven transmembrane receptors. An open reading frame in one of the clones, designated 4C (497 base pairs), displayed approximately 50-60% identity to all of the previously cloned beta-adrenergic receptors (beta-ARs). A lambda-DASH turkey genomic library was screened with a probe generated from the partial 4C cDNA, and the gene encoding this receptor was localized to a 3.5-kilobase pair HindIII fragment. Ribonuclease protection analysis of turkey lung mRNA indicated that the 3' end of the coding sequence of the 4C gene, like beta 3-AR, was interrupted by an intron. To obtain the cDNA sequence of 4C, RNA-polymerase chain reaction was performed using primers complementary to regions identified by ribonuclease protection analysis to be present in 4C mRNA. Comparison of the genomic and cDNA sequences of 4C indicated that the first exon encodes 414 amino acids of the protein, the second exon (68 base pairs) encodes an additional 12 residues followed by a stop codon, and the third exon is composed of 3'-untranslated sequence. The 4C receptor was transiently expressed in COS-1 cells, and the apparent affinities of a series of beta-AR agonists and antagonists were determined using [125I]iodocyanopindolol. As implicated by its amino acid sequence, 4C displayed a pharmacological selectivity that was consistent with that of a beta-AR but distinct from other cloned beta-ARs. Isoproterenol, epinephrine, and norepinephrine stimulated cyclic AMP accumulation in a concentration-dependent manner in mouse L cells stably expressing the 4C receptor. No effect on phospholipase C activity was observed. Ribonuclease protection assays indicated that 4C mRNA exhibits a broad tissue distribution, which suggests that it may play an important role in avian physiology.
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PMID:Molecular cloning and characterization of a novel beta-adrenergic receptor. 792 60

The cDNA for the rat alpha 1c-adrenergic receptor (AR) has been cloned using a probe derived from the bovine alpha 1c-AR sequence. Clone rB7a has a 2.6-kilobase insert with a 1390-base pair open reading frame and encodes a receptor of 466 amino acids. The cloned receptor has 91% amino acid identity with the bovine alpha 1c-AR. The rat alpha 1c-AR mRNA was detected in tissues known to be enriched for the alpha 1A-AR subtype, including vas deferens, heart, kidney, and hippocampus. Rat alpha 1c-AR mRNA was absent from liver and spleen when assayed by Northern blot analyses and RNase protection assays. In COS-7 cells transfected with cDNAs encoding the three rat alpha 1-ARs, WB-4101 and benoxathian had similar binding affinities for the alpha 1a/d-AR and the alpha 1c-AR and 10-fold lower affinities for the alpha 1b-AR. The affinity of 5-methylurapidil was found to be 10- and 30-fold higher at the alpha 1c-AR than at the alpha 1a/d- and alpha 1b-ARs, respectively. (S)-(+)-Niguldipine was found to have high affinity for the rat alpha 1c-AR, with 42- and 22-fold lower affinity at the alpha 1a/d- and alpha 1b-ARs, respectively. Treatment of intact transfected COS-7 cells with chlorethylclonidine resulted in the inactivation of 19% of the alpha 1c-ARs, in contrast to 72% and 85% inactivation of the alpha 1a/d- and alpha 1b-ARs, respectively. Similarly to the other two alpha 1-ARs, the rat alpha 1c-AR is coupled to the activation of phospholipase C. Our data suggest that the rat alpha 1c-AR cDNA encodes an alpha 1-AR with the pharmacological properties previously defined for the alpha 1A subtype found in tissues.
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PMID:The rat homologue of the bovine alpha 1c-adrenergic receptor shows the pharmacological properties of the classical alpha 1A subtype. 793 20

Adenosine potentiates the stimulated release of mast cell mediators. Pharmacologic studies suggest the presence of two adenosine receptors, one positively coupled to adenylate cyclase and the other coupled to phospholipase C activation. To identify mast cell adenosine receptor subtypes, cDNAs for the A1 and A2a adenosine receptors were obtained by screening a mouse brain cDNA library with the use of PCR-derived probes. Mouse bone marrow-derived mast cell cDNA libraries were constructed and screened with the use of A1 and A2a cDNA probes, which revealed the presence of A2a, but not A1, receptor clones. A putative A2b receptor was identified by using low stringency mast cell library screening. Northern blotting of mast cell poly(A)+ RNA with the use of receptor subtype probes labeled single mRNA bands of 2.4 kb and 1.8 kb for the A2a and A2b receptors, respectively. In situ cells. An A2a receptor-specific agonist failed to enhance mast cell mediator release, which suggests that the secretory process is modulated through the A2b and/or another receptor subtype. By using RNase protection assays, we found that mast cells that had been cultured in the presence of N-ethylcarboxamidoadenosine for 24 h exhibited a decrease in both A2a and A2b receptor RNA levels. Cells that had been cultured for 1 to 2 days in the presence of dexamethasone demonstrated increased amounts of A2a receptor mRNA, but no identifiable change in A2b receptor mRNA. Mast cells possess at least two adenosine receptor subtypes that may be differentially regulated.
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PMID:Cloning of two adenosine receptor subtypes from mouse bone marrow-derived mast cells. 815 66

The three cloned alpha1-adrenergic receptor (AR) subtypes, alpha1B, alpha1C, and alpha1D, can all couple to the same effector, phospholipase C, and the reason(s) for conservation of multiple subtypes remain uncertain. All three alpha1-ARs are expressed natively in cultured neonatal rat cardiac myocytes, where chronic exposure to the agonist catecholamine norepinephrine (NE) induces hypertrophic growth and gene transcription. We show here, using RNase protection, that the alpha1-AR subtype mRNAs respond in distinctly different ways during prolonged NE exposure (12 72 h). Alpha1B and alpha1D mRNA levels were repressed by NE, whereas alpha1C mRNA was induced. Changes in mRNA levels were mediated by an alpha1-AR, were not explained by altered mRNA stability, and were reflected in receptor proteins by [3H]prazosin binding. alpha1-AR-stimulated phosphoinositide hydrolysis and myocyte growth were not desensitized. Three other hypertrophic agonists in culture, endothelin-1, PGF2alpha, and phorbol 12-myristate 13-acetate, also induced alpha1C mRNA and repressed alpha1B mRNA. In myocytes from hearts with pressure overload hypertrophy, alpha1 mRNA changes were identical to those produced by NE in culture. These results provide the first example of a difference in regulation among alpha1-AR subtypes expressed natively in the same cell. Transcriptional induction of the alpha1C-AR could be a mechanism for sustained growth signaling through this receptor and is a common feature of a hypertrophic phenotype in cardiac myocytes.
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PMID:Alpha1-adrenergic receptor subtype mRNAs are differentially regulated by alpha1-adrenergic and other hypertrophic stimuli in cardiac myocytes in culture and in vivo. Repression of alpha1B and alpha1D but induction of alpha1C. 862 54


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