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)

A phosphatidylinositol phosphodiesterase from the culture broth of Bacillus cereus, was purified to a homogeneous state as indicated by polyacrylamide gel electrophoresis, by ammonium sulfate precipitation and chromatography with DEAE-cellulose and CM-Sephadex. The enzyme (molecular weight: 29000 +/- 1000) was maximally active at pH 7.2-7.5, AND NOT INFLUENCED BY EDTA, ophenanthroline, monoiodoacetate, p-chloromercuribenzoate or reduced glutathione. The enzyme specifically hydrolyzed phosphatidylinositol, but did not act on phosphatidylcholine, phosphatidylethanolamine and sphingomyelin, under the conditions examined. The products from phosphatidylinositol of enzyme reaction were diacylglycerols and a mixture of myoinositol 1- and 1, 2-cyclic phosphates, suggesting that the enzyme was a phosphatidylinositol-specific phospholipase C. The enzyme released alkaline phosphatase quantitatively from rat kidney slices. A kinetic analysis was made on the release of alkaline phosphatase. The results suggest that phosphatidylinositol-specific phospholipase C can specifically act on plasma membrane of rat kidney slices.
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PMID:Studies on phosphatidylinositol phosphodiesterase (phospholipase C type) of Bacillus cereus. I. purification, properties and phosphatase-releasing activity. 1 Sep 86

The release of plasma membrane ecto-enzymes by a phosphatidylinositol-specific phospholipase C from Staphylococcus aureus was investigated. There was no effect on L-leucyl-beta-naphthylamidase, alkaline phosphodeisterase I and Ca2+- or MG2+-ATPase, but substantial proportions of the alkaline phosphatase and 5-nucleotidase were released. There was no simultaneous release of phospholipid and the solubilized enzymes were not exluded from Sepharose 6-B. It was therefore concluded that release was not a secondary consequence of membrane vesiculation but occurred as a result of the disruption of specific interactions involving the phosphatidylinositol molecule.
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PMID:Specific release of plasma membrane enzymes by a phosphatidylinositol-specific phospholipase C. 20 48

We provide evidence that the mechanism for arachidonate release from stimulated human platelets involves two enzymes: a phosphatidylinositol-specific phospholipase C (EC 3.1.4.10) and a diglyceride lipase. After incubation of platelets with thrombin for 15 seconds, 1.2 nmol of 1-stearoyl-2-arachidonoyl diglyceride per 10(9) platelets, was isolated. Arachidonate was released from this substrate by the action of diglyceride lipase located in the particulate fraction of platelets. The enzyme has a pH optimum of 7.0, is stimulated by calcium ions and reduced glutathione, and liberates 31 nmol of fatty acid per min per mg of platelet particulate protein. The diglyceride lipase has sufficient activity to account for the 5-10 nmol of arachidonate released per 10(9) platelets upon thrombin stimulation. That only arachidonate is released upon thrombin stimulation may be explained by the fact that the diglyceride substrate in platelets contains only arachidonate in the 2 position. The lipase activity found in platelet membranes can also hydrolyze the 1-position fatty acid. Stearate is not released when intact platelets are stimulated with thrombin, and the fate of this fatty acid remains to be elucidated.
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PMID:Diglyceride lipase: a pathway for arachidonate release from human platelets. 29 Sep 99

(1) The hydrolysis of (32)P- or myo-[2-(3)H]inositol-labelled rat liver microsomal phospholipids by rat liver lysosomal enzymes has been studied. (2) The relative rates of hydrolysis of phospholipids at pH4.5 are: sphingomyelin>phosphatidylethanolamine>phosphatidylcholine> phosphatidylinositol. (3) The predominant products of phosphatidylcholine and phosphatidylethanolamine hydrolysis are their corresponding lyso-compounds, indicating a slow rate of total deacylation. (4) Ca(2+) inhibits the hydrolysis of all phospholipids, though only appreciably at high (>5mm) concentration. The hydrolysis of sphingomyelin is considerably less sensitive to Ca(2+) than that of glycerophospholipids. (5) Analysis of the water-soluble products of phosphatidylinositol hydrolysis (by using myo-[(3)H]inositol-labelled microsomal fraction as a substrate) produced evidence that more than 95% of the product is phosphoinositol, which was derived by direct cleavage from phosphatidylinositol, rather than by hydrolysis of glycerophosphoinositol. (6) This production of phosphoinositol, allied with negligible lysophosphatidylinositol formation and a detectable accumulation of diacylglycerol, indicates that lysosomes hydrolyse membrane phosphatidylinositol almost exclusively in a phospholipase C-like manner. (7) Comparisons are drawn between the hydrolysis by lysosomal enzymes of membrane substrates and that of pure phospholipid substrates, and also the possible role of phosphatidylinositol-specific lysosomal phospholipase C in cellular phosphatidylinositol catabolism is discussed.
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PMID:Hydrolysis of membrane phospholipids by phospholipases of rat liver lysosomes. 50 1

Purified phosphatidylinositol-specific phospholipase C from Staphylococcus aureus released a substantial proportion of the total alkaline phosphatase activity from a wide range of tissues from several mammalian species. Co-purification of the phospholipase C and alkaline phosphatase-releasing activities and the inhibition of both these activities by iso-osmotic salt solutions suggested that the releasing effect was unlikely to be due to a contaminant.
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PMID:Release of alkaline phosphatase from membranes by a phosphatidylinositol-specific phospholipase C. 58 58

A phosphatidylinositol-specific phospholipase C from Staphylococcus aureus was purified by a three-step procedure. The specific activity of the purified enzyme was approx. 6000 times that of the culture supernatant, with an overall recovery of approx. 10%. Estimation of the molecular weight by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and by gel filtration gave values of 33000 and 20000 respectively. A thiol group appears to be necessary for the activity of the enzyme. The purified enzyme had no detectable delta-haemolytic activity and was unable to hydrolyse S. aureus phospholipids. Phosphatidyl-inositol in erythrocyte 'ghosts' was readily hydrolysed by the purified phospholipase C. However, in contrast with our previous preliminary observations, phosphatidylinositol in intact erythrocytes was not significantly hydrolysed. These results suggest that at least 75-80% of the phosphatidylinositol is located at the inner leaflet of the membrane.
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PMID:Modification of erythrocyte membranes by a purified phosphatidylinositol-specific phospholipase C (Staphylococcus aureus). 84 83

Orthovanadate is an agent known to stimulate cell growth and mimic insulin action. The effects of this compound on phosphoinositides in NIH 3T3 cells were examined. Both 100 and 1000 microM orthovanadate were found to increase the cellular content of inositol phosphate secondary to the activation of phosphatidylinositol-specific phospholipase C (PtdIns-PLC). The time course, dependence on orthovanadate concentration, and sensitivity to the isoflavone genistein were similar for orthovanadate-induced accumulation of inositol phosphate and protein tyrosine phosphate, indicating that there is a correlation between cellular protein tyrosine phosphate levels and PtdIns-PLC activity. Increased phosphatidylinositol phosphate (PtdInsP) content also occurred when cells were incubated with orthovanadate and appeared to result from the activation of PtdIns kinase. This effect was not correlated with cellular protein tyrosine phosphate content. Hence, orthovanadate is shown to affect phosphoinositide metabolism at a minimum of two sites by both tyrosine phosphate-dependent and -independent mechanisms.
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PMID:The effect of orthovanadate on phosphoinositide metabolism in NIH 3T3 fibroblasts. 130 96

We have isolated a full-length cDNA for human carbonic anhydrase IV (CA IV) from a lambda gt10 human kidney cDNA library. The 1105-base-pair (bp) cDNA contains a 47-bp 5' untranslated region, a 936-bp open reading frame, and a 122-bp 3' untranslated region. The deduced amino acid sequence is colinear with the N-terminal sequence and the sequence of several tryptic peptides of human lung CA IV. It includes an 18-amino acid signal sequence, a 260-amino acid region that shows 30-36% similarity with the 29-kDa cytoplasmic CAs (CA I, CA II, and CA III), and an additional 27-amino acid C-terminal sequence that ends in a 21-amino acid hydrophobic domain. Of the 17 "active site" residues that are highly conserved in other human CAs, 16 are also present in CA IV. Expression of the cDNA in COS cells produced a 35-kDa enzyme that was membrane associated, resistant to inactivation by SDS, contained no carbohydrate, and reacted on Western blots with antiserum to the 35-kDa CA IV from human lung. Treatment of membranes from transfected COS cells with phosphatidylinositol-specific phospholipase C released 20-30% of the expressed enzyme from membranes, indicating that at least 20-30% of the expressed enzyme was anchored to membranes by a glycosyl-phosphatidylinositol linkage.
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PMID:Human carbonic anhydrase IV: cDNA cloning, sequence comparison, and expression in COS cell membranes. 131 Oct 94

The extent to which eosinophils constitutively express FcRIII (CD16) is controversial. We were unable to detect this receptor on freshly isolated, peripheral blood eosinophils. The capacity of eosinophils to change their Fc gamma R expression in vitro has not been previously demonstrated. Culture with IFN-gamma for 1 to 2 days induced FcRIII expression on eosinophils. This effect was dose-dependent and significant at concentrations of 100 U/ml IFN-gamma and above. Expression of FcRI (CD64) and FcRII (CDw32) was also upregulated. These increases were inhibited by cycloheximide (10(-6) M), suggesting a requirement for protein synthesis, and dexamethasone (10(-6) M). Northern blot analysis demonstrated the presence of FcRIII mRNA in eosinophils cultured with IFN-gamma for 2 days but not in unstimulated eosinophils. By contrast, culture with IL-3 caused an up-regulation of eosinophil FcRII expression but did not induce expression of FcRI or FcRIII. The FcRIII expressed by eosinophils after IFN-gamma stimulation was functionally active, as shown by the triggering of eosinophil membrane depolarization and LTC4 generation by an anti-CD16 mAb. Treatment of IFN-gamma-stimulated eosinophils with phosphatidylinositol-specific phospholipase C reduced FcRIII expression, suggesting that, like neutrophils, eosinophils express the phosphatidylinositol glycan-linked form of this receptor. Therefore, this study demonstrates that IFN-gamma-treated eosinophils express a functionally active, phosphatidylinositol glycan-anchored form of FcRIII.
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PMID:IFN-gamma induces expression of Fc gamma RIII (CD16) on human eosinophils. 131 48

To study the role of membrane lipids in signal transduction by the insulin receptor, we have studied the effect of phospholipase C (Clostridium perfringens) and a phosphatidylinositol-specific phospholipase (Staphylococcus aureus) on insulin binding, a function of the alpha-subunit, and tyrosine kinase activity, a function of the beta-subunit in IM-9 lymphocytes and NIH 3T3 fibroblasts transfected with the human insulin receptor. Treatment of the cells with phospholipase C at concentrations up to 3.4 U/ml did not affect specific insulin binding, but reduced insulin-stimulated receptor phosphorylation by 50%. This effect of phospholipase C was observed within 10 min of treatment and occurred with no change in the basal level of phosphorylation. Pre-treatment of cells with insulin for 5 min prior to enzyme addition prevented any change in kinase activity. Insulin-stimulated phosphorylation of pp 185, the presumed endogenous substrate for the insulin receptor kinase, was also reduced following phospholipase C treatment, with an almost complete loss of insulin stimulation after exposure of cells to enzyme at concentrations as low as 0.6 U/ml. In contrast to these effects of phospholipase C on intact cells, receptor autophosphorylation was not affected in insulin receptors purified on wheat germ agglutinin-agarose from phospholipase C treated cells. Likewise, the phospholipase C effect was reduced by the addition of phosphatidylcholine, but not by the addition of the protease inhibitors, aprotinin and phenylmethylsulfonyl fluoride, to the incubation indicating its dependence on phospholipid hydrolysis. Treatment of cells with the phosphatidylinositol-specific phospholipase C did not affect any of the parameters studied.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of phospholipase treatment on insulin receptor signal transduction. 131 92


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