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)

rac-Phosphatidyl carnitine and rac-phosphatidyl beta-methylcholine were synthesized by direct condensation of phosphatidic acid and the appropriate alcohols in the presence of 2,4,6-triiso-propylbenzenesulphonylchloride and pyridine. Tetraphenylborates of the quarternary ammonium compounds beta-methylcholine and carnitine benzyl ester were shown to be particularly convenient for synthesis in homogeneous phase. Physical and chemical properties of the two phosphoglycerolipids and some intermediates were described. Phosphatidyl carnitine and phosphatidyl beta-methylcholine were hydrolyzed by phospholipase A2 (phosphatide acyl-hydrolase, EC 3.1.1.4), pancreatic lipase (triacylglycerol acyl-hydrolase, EC 3.1.1.3), and phospholipase C from Bacillus cereus (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3). Neither hydrolysis nor transphosphatidylation of phosphatidyl carnitine and phosphatidyl beta-methylcholine was achieved by phospholipase D (phosphatidylcholine phosphatidohydrolase, EC 3.1.4.4). The occurrence of phosphatidyl carnitine in embryonic chicken tissue was suggested by comparison with the synthesized compound. Phosphatidyl carnitine could not be detected in the tissue of rat embryos.
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PMID:Synthesis and properties of phosphatidyl carnitine and phosphatidyl beta-methylcholine. 80 79

The release of beta-lysin, which followed the intravenous injection of antigen-antibody complexes, did not take place when these complexes were added to citrated whole blood but did occur in heparinized blood. beta-Lysin release in heparinized blood was inhibited by citrate but were reversed by the addition of calcium ions that implicated complement reactions. Fourteen different enzymes were added to platelet-rich plasma (PRP). Streptokinase, neuraminidase, papain, phospholipase C, sulfatase, and trypsin caused platelets to release significant quantities of beta-lysin, whereas elastase, phosphatase, protease, ribonuclease A, hyaluronidase, lipase, and pepsin caused little or no increase in the plasma beta-lysin concentration. One enzyme, fibrinolysin, inactivated beta-lysin faster than it was released. The enzyme-induced release of beta-lysin from PRP was often accompanied by a reduction in the number of platelets. The intravenous injection of streptokinase, neuraminidase, and sulfatase caused in vivo releases of beta-lysin into the plasma. The platelet-aggregating substances collagen, arachidonic acid, and adenosine 5'-diphosphate caused beta-lysin to be released from PRP. The platelet-aggregating substances L-epinephrine, zymosan, fibrinogen, reserpine, and serotonin caused little or no release of beta-lysin from platelets. The results of this study indicate that the release of beta-lysin during antigen-antibody-complement reactions, blood coagulation, phagocytosis, and inflammation could be enzyme mediated.
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PMID:Release of beta-lysin from platelets caused by antigen-antibody complexes, purified enzymes, and platelet-aggregating substances. 84 4

1. The properties of rat liver cytoplasmic alpha-tocopherol binding protein have been studied. 2. The binding protein sedimented in the 3 S region of sucrose density gradients, and gel filtration indicated an approximate molecular weight of 30 500. 3. Of the tissues examined by the present assay, binding was detectable only in the liver. 4. Optimal binding was achieved by incubation at 26 degrees C for 4 h and was independent of pH between 7.4 and 9.0. 5. Pronase completely abolished binding. The binding protein was, however, almost completely resistant to trypsin, and unaffected by RNAase, DNAase, triacylglycerol lipase, and phospholipase C. 6. A variety of tocopherol analogues and other lipid-soluble compounds were tested for their ability to compete for binding. Only alpha-tocopherol and to a lesser extent alpha-tocotrienol and gamma-tocopherol exhibited competition. alpha-Tocopherol acetate, alpha-tocopherol quinone and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid had no effect on binding. 7. Tocopherol binding was reversible, and the tocopherol was not metabolized during incubation.
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PMID:Rat liver alpha-tocopherol binding protein. 87 71

Heavy beef heart mitochondria depleted of phospholipids by treatment with phospholipase C followed by removal of the by products by lipase treatment or sonication in pentane were analyzed by electron microscopy, chemical analysis and assays of enzymatic activities. The results indicate that diglycerides are present after phospholipase C treatment and are inhibitors of NADH-cytochrome c reductase. After removal of diglycerides with lipase treatment, a phospholipid requirement for NADH-cytochrome c reductase could be demonstrated.
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PMID:Phospholipase C treatment of mitochondria. 92 60

A simple method is reported for the determination of GPL in serum, requiring small amount of sample and adequate for screening of large population groups. The method is based on the release of glycerol portion of the phospholipid molecule by the combined action of phospholipase C and lipase. The glycerol is then determined by well established methods. The importance of screening of lecithin, that accounts for more than 84% of the glycerophospholipids of serum lipoproteins, is discussed in view of lipoprotein function and structure and in view of interaction between lipoproteins and plasma membranes.
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PMID:A completely enzymatic method for the determination of glycerophospholipids in human serum. 102 16

Thy-1 is a major cell surface protein anchored in the plasma membrane of neurons and lymphocytes by a covalent glyco-phosphatidyl-inositide linkage. Despite thorough characterization of the molecule's physicochemical properties, its biological function remains elusive. In this study we demonstrate that (i) monoclonal antibodies directed against Thy-1 are capable of enhancing neurite outgrowth from sympathetic neurons in culture, as well as stimulating the initiation of neurite sprouting from cultured adrenal chromaffin cells and PC12 cells. This effect is not observed with monovalent, Fab antibody fragments. Treatment with intact antibodies also results in the shedding of Thy-1 into the culture medium. (ii) Treatment of chromaffin cells with phosphatidyl-inositol-specific phospholipase C also results in an induction of neurite sprouting. The lipase effect can be blocked by preincubating the cells with monovalent anti-Thy-1 Fab fragments, indicating that the outgrowth stimulation is specifically due to removal of Thy-1. (iii) An entirely different approach to elucidating the function of Thy-1 involves mutagenesis of PC12 cells. Selection for Thy-1-deficient mutants revealed that cells lacking Thy-1 sprout neurites spontaneously at a very high frequency. A novel role for Thy-1 is proposed wherein the results of the mutant cell studies are compatible with the antibody and lipase data. Each of the perturbations can be viewed as releasing an inhibition that Thy-1 normally exerts on neurite outgrowth. We suggest that Thy-1 normally acts to stabilize neuronal membranes and processes, possibly through homophilic interactions.
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PMID:Thy-1 involvement in neurite outgrowth: perturbation by antibodies, phospholipase C, and mutation. 134 21

Qa-2 antigen, a nonclassical MHC antigen, is one of a group of cell surface antigens that may be anchored to the cell surface by a glycophosphatidylinositol (GPI) linkage rather than, as is the case with the classical MHC antigens, K, D, and L, by a transmembrane linkage. Recent studies have shown that T cells may be activated through the cross-linking of GPI anchored Qa-2 antigens by anti-Qa-2 antiserum. The Qa-2 antigens involved in signal transduction in activated T cells are sensitive to lipolytic cleavage by phosphatidylinositol-dependent-phospholipase C (PI-PLC). Since T cell function is known to decline with age, a study was undertaken to determine whether the relative amount of lipase sensitive Qa-2 antigen changes with age. Ficoll- Hypaque purified peripheral blood lymphocytes were obtained from C57BL/6 and A strain mice from 6-30 months of age. The cells were incubated with or without phosphatidylinositol- dependent-phospholipase C followed by incubation with anti-Qa-2 monoclonal antibodies and a fluorescein labeled second antibody. Analysis on a FACScan flow cytometer demonstrated that the A strain mice had a single population of Qa-2 positive lymphocytes which increased in lipase sensitivity with age. The C57BL/6 strain mice of all ages had two populations of Qa-2 positive cells, one staining with high fluorescence intensity (high antigen density) and the other with low fluorescence intensity (low antigen density). The proportion of cells found in the high density peak increased markedly with age, suggesting on overall increase in Qa-2 expression. In young animals, only the high density peak was sensitive to PI-PLC treatment. In older animals, the cells originally appearing in the high density population shifted to the low density population after treatment with PI-PLC, suggesting that there must be both lipase sensitive and lipase insensitive forms of Qa-2 present on lymphocytes in these aging C57BL/6 mice. Overall, these data suggest that the proportion of lymphocytes expressing lipase sensitive Qa-2 is increased on lymphocytes of old mice. Since a role for lipase sensitive GPI-linked Qa-2-antigen has recently been postulated in T cell activation, it is possible that the increased lipase sensitive Qa-2 antigen may play a role in age-related changes in T cell function.
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PMID:Expression of phosphatidylinositol-dependent phospholipase C sensitive Qa-2 antigen is increased on peripheral blood lymphocytes of aging mice. 148 61

There is evidence suggesting that fluid shear stress activates phospholipid turnover in endothelial cells, but it is not clear which phospholipids are involved in the transduction of the flow signal. Cultured human umbilical-vein endothelial cells were prelabeled with [14C]-arachidonic acid and subjected to laminar shear stresses of 0.4, 1.4 and 22 dyn/cm2 for times up to 30 min, after which the distribution of the radioactivity in the phospholipids was determined. We observed decreases in labeled phosphatidylinositol, phosphatidylethanolamine and phosphatidic acid at 10-30 s, and increases in labeled diacylglycerol (DG) and free arachidonate, as well as a simultaneous elevation in inositol 1,4,5-triphosphate (IP3) levels. A second peak in IP3 levels was observed 10 min after the onset of shear. This is in contrast with agonist-stimulated endothelial cells, where IP3 levels go back to initial values within a few minutes after stimulation. The flow-induced IP3 response was the same in the presence or absence of ATP and serum in the perfusing medium. These results are consistent with the activation of phospholipase C, phospholipase A2 and DG lipase by shear stress. This suggests that several phospholipids are involved in the production of free arachidonic acid and DG, which are likely to be important mediators of the shear stress signal. In addition, flow may lead to a chronic stimulation of endothelial-cell metabolism.
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PMID:Fluid shear stress stimulates membrane phospholipid metabolism in cultured human endothelial cells. 148 90

125I-epsilon-toxin showed high affinity to rat brain homogenates and synaptosomal membrane fractions, having single binding phases with dissociation constants (Kds) of 2.5 and 3.3 nM, respectively. Treatment of synaptosomal membrane fractions with pronase and neuraminidase lowered the binding of the labeled toxin, whereas treatment with trypsin and phospholipase C did not. Heating of the fractions resulted in a decrease in the binding of the toxin. These data suggest that interaction of epsilon-toxin with cell membranes in the brain is facilitated by a sialoglycoprotein. On the other hand, treatment of the membrane fractions with lipase resulted in complete loss of binding, suggesting that the interaction may require an appropriate lipid environment. These data suggest the presence of specific binding sites in brain tissue for epsilon-toxin.
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PMID:High-affinity binding of Clostridium perfringens epsilon-toxin to rat brain. 154 39

The involvement of endogenous diacylglycerol production in the stimulation of phosphatidylcholine synthesis by exogenous phospholipase C was examined using a neuroblastoma (LA-N-2) cell line. Phospholipase C treatment (0.1 unit/ml) of intact cells stimulated CTP:phosphocholine cytidylyltransferase activity significantly more effectively than did maximally effective concentrations of the synthetic diacylglycerol sn-1,2-dioctanoylglycerol (1 mM). When added to cells together with phospholipase C, oleic acid, but not dioctanoylglycerol, further increased cytidylyltransferase activity with respect to phospholipase C treatment alone, indicating that the enzyme was not maximally activated by the lipase. This suggests that the lack of additivity of diacylglycerol and phospholipase C reflects a common mechanism of action. The time course of activation of cytidylyltransferase by phospholipase C paralleled that of [3H]diacylglycerol production in cells prelabeled for 24 h with [3H]oleic acid. Diacylglycerol mass was similarly increased. Significant elevations of [3H]oleic acid and total fatty acids occurred later than did the increases in cytidylyltransferase activity and diacylglycerol levels. No significant reduction in total or [3H]phosphatidylcholine was elicited by this concentration of phospholipase C, but higher concentrations (0.5 unit/ml) significantly reduced phosphatidylcholine content. The stimulation of cytidylyltransferase activity by phospholipase C or dioctanoylglycerol was also associated with enhanced incorporation of [methyl-14C]choline into phosphatidylcholine. Dioctanoylglycerol was more effective than phospholipase C at stimulating the formation of [14C]phosphatidylcholine, and the effects of the two treatments were additive. However, further analysis revealed that dioctanoylglycerol served as a precursor for [14C]dioctanoylphosphatidylcholine as well as an activator of cytidylyltransferase; and when corrections were made for this effect, the apparent additivity disappeared. The results indicate that the generation of diacylglycerol by exogenous phospholipase C (and possibly the subsequent production of fatty acids via diacylglycerol metabolism) activates cytidylyltransferase activity in neuronal cells under conditions in which membrane phosphatidylcholine content is not measurably reduced.
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PMID:Production of diacylglycerol by exogenous phospholipase C stimulates CTP:phosphocholine cytidylyltransferase activity and phosphatidylcholine synthesis in human neuroblastoma cells. 166 12


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