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)

The glycoinositol phospholipid membrane anchor of human erythrocyte acetylcholinesterase (EC 3.1.1.7) is composed of a glycan linked through a glucosamine residue to an inositol phospholipid that is resistant to the action of phosphatidylinositol-specific phospholipase C. Deamination cleavage of the glucosamine with nitrous acid released the inositol phospholipid which was purified by high performance liquid chromatography. Analysis by fast atom bombardment mass spectrometry with negative ion monitoring and by the complementary technique of collision-induced dissociation revealed molecular and daughter ions that indicated a plasmanylinositol with a palmitoyl group on an inositol hydroxyl. The intact membrane anchor was released from reductively methylated human erythrocyte acetylcholinesterase by proteolysis with papain or Pronase, deacylated by base hydrolysis, and purified by high performance liquid chromatography. Positive and negative ion fast atom bombardment mass spectrometry of the major products isolated by high performance liquid chromatography indicated the following structure for the complete glycoinositol phospholipid anchor. (formula; see text) Methylation of free amino groups by reduction with deuterium instead of hydrogen permitted determination of the number of free amino groups in individual fragment ions as further confirmation of structural assignments. The structure of the glycan portion of the human erythrocyte acetylcholinesterase membrane anchor appears to be similar to that described for Trypanosome brucei variant surface glycoprotein MITat 1.4 (variant 117) (Ferguson, M.A.J., Homans, S.W., Dwek, R.A., and Rademacher, T.W. (1988) Science 239, 753-759) except for the absence of a galactose antenna and the presence of a phosphorylethanolamine on the hexose adjacent to glucosamine.
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PMID:Structural characterization of the glycoinositol phospholipid membrane anchor of human erythrocyte acetylcholinesterase by fast atom bombardment mass spectrometry. 284 7

Thy-1 is a developmentally regulated cell surface glycoprotein in nervous tissue. An inositol-containing glycolipid structure is covalently attached to its carboxyl terminus, which anchors the protein to the cell membrane. In the present paper we report the characterization of a water-soluble form of Thy-1, purified from human cerebrospinal fluid (CSF). In contrast to the membrane-bound form of Thy-1 (M-Thy-1) isolated from human brain cerebral cortex, CSF-Thy-1 behaved like a completely hydrophilic glycoprotein, as analyzed by charge-shift electrophoresis in the presence of detergents and by liposome incorporation experiments. CSF-Thy-1 displayed a slightly higher apparent molecular weight in sodium dodecyl sulfate-polyacrylamide gel electrophoresis than M-Thy-1. Digestions with endoglycosidases demonstrated that this difference in size was correlated to different processing of the three N-linked oligosaccharides, and the mobilities of the deglycosylated molecules were indistinguishable in sodium dodecyl sulfate gels. A Pronase-resistant carboxyl-terminal fragment was isolated from the CSF-Thy-1 after trypsin digestion and compared with the corresponding structure of M-Thy-1, obtained by treatment either with bacterial phosphatidylinositol-specific phospholipase C or with human serum (as a source of phosphatidylinositol-specific phospholipase D). The major fragment from CSF-Thy-1 behaved identically, with respect to size and charge, to the carboxyl-terminal fragment from M-Thy-1 solubilized by phospholipase D. These findings suggest an in vivo release of phosphatidylinositol-anchored Thy-1 glycoprotein from brain cells by the action of an endogenous phospholipase D.
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PMID:Characterization of a hydrophilic form of Thy-1 purified from human cerebrospinal fluid. 290 Aug 38

Biosynthetic labelling experiments with cercariae and schistosomula of the multicellular parasitic trematode Schistosoma mansoni were performed to determine whether [3H]palmitate or [3H]ethanolamine was incorporated into proteins. Parasites incorporated [3H]palmitate into numerous proteins, as judged by SDS/polyacrylamide-gel electrophoresis and fluorography. The radiolabel was resistant to extraction with chloroform, but sensitive to alkaline hydrolysis, indicating the presence of an ester bond. Further investigation of the major 22 kDa [3H]palmitate-labelled species showed that the label could be recovered in a Pronase fragment which bound detergent and had an apparent molecular mass of 1200 Da as determined by gel filtration on Sephadex LH-20. Schistosomula incubated with [3H]ethanolamine for up to 24 h incorporated this precursor into several proteins; labelled Pronase fragments recovered from the three most intensely labelled proteins were hydrophilic and had a molecular mass of approx. 200 Da. Furthermore, reductive methylation of such fragments showed that the [3H]ethanolamine bears a free amino group, indicating the lack of an amide linkage. We also evaluated the effect of phosphatidylinositol-specific phospholipase C from Staphylococcus aureus: [3H]palmitate-labelled proteins of schistosomula and surface-iodinated proteins were resistant to hydrolysis with this enzyme. In conclusion, [3H]palmitate and [3H]ethanolamine are incorporated into distinct proteins of cercariae and schistosomula which do not bear glycophospholipid anchors. The [3H]ethanolamine-labelled proteins represent a novel variety of protein modification.
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PMID:Characterization of [3H]palmitate- and [3H]ethanolamine-labelled proteins in the multicellular parasitic trematode Schistosoma mansoni. 317 67

The membrane form of Trypanosoma brucei variant surface glycoprotein (mfVSG) is acylated with ester-linked tetradecanoic (myristic) acid (Ferguson, M. A. J., and Cross, G. A. M. (1984) J. Biol. Chem. 259, 3011-3015). Comparative analysis of Pronase peptides from mfVSG and soluble VSG localizes the site of mfVSG acylation to a COOH-terminal oligosaccharide structure. Chemical and enzymatic treatment of the acylated Pronase mfVSG fragment revealed that the myristic acid is present as a diglyceride (sn-1,2-dimyristin) that is probably linked to the COOH-terminal oligosaccharide via a phosphodiester bond between the sn-3-glycerol hydroxyl and a sugar hydroxyl group. The endogenous membrane-associated enzyme, which quantitatively cleaves myristic acid from mfVSG to produce soluble VSG, releases diglyceride, as would be expected of a phospholipase C.
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PMID:Trypanosoma brucei variant surface glycoprotein has a sn-1,2-dimyristyl glycerol membrane anchor at its COOH terminus. 398 41

The COOH terminus of the externally disposed variant surface glycoprotein (VSG) of the eukaryotic pathogenic protozoan Trypanosoma brucei strain 427 variant MITat 1.4 (117) is covalently linked to a novel phosphatidylinositol-containing glycolipid. This conclusion is supported by analysis of the products of nitrous acid deamination or Staphylococcus aureus phosphatidylinositol-specific phospholipase C treatment of purified membrane-form VSG. Lysis of trypanosomes is accompanied by release of soluble VSG, catalyzed by activation of an endogenous phospholipase C. The only apparent difference between membrane-form VSG and soluble VSG is the removal of sn-1,2-dimyristylglycerol. The COOH-terminal glycopeptide derived by Pronase digestion of soluble VSG was characterized by chemical modification and digestion with alkaline phosphatase. The results are consistent with the single non-N-acetylated glucosamine residue being the reducing terminus of the oligosaccharide and in a glycosidic linkage to a myo-inositol monophosphate that is probably myo-inositol 1,2-cyclic monophosphate. A partial structure for the VSG COOH-terminal moiety is presented. This structure represents a new type of eukaryotic post-translational protein modification and membrane anchor. We discuss the relevance of this structure to observations that have been made with other eukaryotic membrane proteins.
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PMID:Glycosyl-sn-1,2-dimyristylphosphatidylinositol is covalently linked to Trypanosoma brucei variant surface glycoprotein. 405 88

A Mycoplasma gallisepticum subcellular fraction (P2), which contains the deoxyribonucleic acid replication complex, can be isolated by differential centrifugation of freeze-thaw-lysed cells. The nascent deoxyribonucleic acid is released from P2 by Lubrol-WX, sodium dodecyl sulfate, Pronase, and deoxyribonuclease, but not by saponin, ribonuclease, phospholipase C, or high-frequency sonic treatment. Sonic treatment further fractionates the cell ghost and allows partial purification, on sucrose density gradients, of a deoxyribonucleic acid replication complex attached to the cells' polar membrane-bleb-infrableb structures.
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PMID:Partial purification of a membrane-associated deoxyribonucleic acid complex from Mycoplasma gallisepticum. 442 Sep 60

Cell envelopes of Chromobacterium violaceum were isolated and treated under controlled conditions with trypsin, Pronase, lipase, phospholipase C, lysozyme, and a mixture of enzymes produced by a bacteriolytic Pseudomonas sp. After each enzyme treatment, losses in dry weight, protein, lipid, carbohydrate, 2,6-diaminopimelic acid, and total phosphorus were determined. Electron-microscopic examination of the enzyme-treated envelopes indicated complete or partial loss of envelope rigidity or some envelope fragmentation, or both. Each enzyme hydrolyzed at least one envelope component and liberated several others into the supernatant fluid, where they appeared as nondialyzable particulate components, identified by means of electron microscopy. Unlike the other enzymes, the Pseudomonas sp. enzyme mixture partially liberated all major envelope components except phosphorus, heptose, and 2-keto-3-deoxy octonic acid. In spite of these large losses, the envelopes preserved some features of their integrity and elongated shape.
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PMID:Effect of enzymes on the composition and structure of Chromobacterium violaceum cell envelopes. 577 32

Prostaglandin E2 (PGE2) seems to stimulate cAMP accumulation in ovaries of all mammals. While it acts through specific receptors in some species, our earlier observations (1) suggest absence of PGE2 receptors in the rat ovary. In order to further substantiate this assumption we digested ovarian membranes from the bovine and the rat with various enzymes and measured cAMP after stimulation with PGE2, NaF, and hCG. Pronase, trypsin, and phospholipase C abolished cAMP accumulation completely. Neuraminidase, beta-galactosidase and phospholipase D did not interfere with cAMP formation. After treatment with phospholipase A2, PGE2-mediated cAMP accumulation was abolished in the bovine but not in the rat ovary. Formation of cAMP disappeared after hCG but not after NaF in both species. Furthermore specific binding of PGE2 could not be demonstrated in phospholipase A2-treated bovine ovaries. These findings are consistent with presence of specific PGE2 receptors in the bovine and their absence in the rat ovary.
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PMID:Further evidence for lack of specific receptors for PGE2 in the rat ovary. 614 70

A remarkable and immediate decrease in GDP-mannose:retinyl phosphate mannosyltransferase activity was found on pre-incubation of rat liver postnuclear membranes with phospholipase A2 or phospholipase C. Under the same conditions of pre-incubation (1 min at 37 degrees C) trypsin did not affect the enzyme activity, whereas pre-incubation for 30 min with trypsin and Pronase abolished enzyme activity. The lipid extract of untreated rat liver membranes partially restored enzyme activity after phospholipase treatment. Sphingomyelin was as active as the endogenous lipids. Other phospholipids were less active in the following order: phosphatidylcholine greater than phosphatidylethanolamine greater than phosphatidylinositol = phosphatidylserine. Dolichyl phosphate mannose synthesis was inhibited less (33%) by phospholipase C than was Ret-P-Man synthesis (98.5%) under identical conditions of incubation, which included 0.025% Triton. However, retinyl phosphate mannose synthesis by purified endoplasmic reticulum was found to be resistant to phospholipase C. Mixing experiments failed to demonstrate an inhibitory effect of the phospholipase-treated postnuclear membrane fraction on the synthetic activity of the endoplasmic reticulum, thus excluding the release of an inhibitory factor from the postnuclear membranes.
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PMID:Retinyl phosphate mannose synthesis in rat liver membranes. Phospholipase sensitivity and phospholipid requirement. 619 16

Two soluble forms of AChE from lymphocyte membrane have been obtained, the Triton solubilized Sd form and the high molar salt solubilized Ss form. They present similar Km (0.10 mM). Hydrodynamic properties of these forms have been studied on saccharose gradients with and without detergent or salt. A similar sedimentation coefficient has been found for these two forms (5.7 S). Lymphocyte plasma membrane AChE is a dimeric form (G2). Without detergent, the Sd form shows multiple secondary forms due to main form polymerization. Increase of NaCl concentration (2M) gives rise to a partial dissociation of these polymers. In the same conditions, the Ss form is not affected. The Ss form centrifugated on cesium chloride gradient has a higher density than the Sd form. These two forms have been treated by HPLC: the Stokes radii are respectively 7.1 nm for the Sd form and 4.5 nm for the Ss form. The molecular weights have been estimated at 175 000 for the Sd form and 105 000 for the Ss form. Pronase enzymatic digestion shows that the Ss form is more rapidly inactivated than the Sd form. Phospholipase C inhibits the Ss form and indicates that this form is a lipid-enzyme complex. The Sd form presents a different behaviour: this form is first activated, and afterwards inhibited by phospholipase C. This behaviour could be due to a more preponderant lipidic environment for the Sd form. The Sd form is probably a detergent-lipid-enzyme complex with an important hydrophobocity. These two forms can be explained by a different association between the enzyme and the phospholipids at the plasma membrane.
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PMID:[Properties and characterization of soluble forms of lymphocyte acetylcholinesterase from an ox]. 674 96


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