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)

Erythromycine (EM) and chrolamphenicol (CP), the inhibitors of protein synthesis, were quantitatively examined for the growth of Pseudomonas aeruginosa EA83 and its production of extracellular proteins. The minimal inhibitory concentration (MIC) of EM for the strain was higher than 100 micrograms/ml and that of CP was 100 micrograms/ml. The growth curve of EA83 was not influenced by adding 5 micrograms/ml of EM to the broth culture, but proteolytic activity and the total protein in the culture supernate went down to 60% of the control. Number of organisms in 20 hour culture was almost constant regardless of EM concentration ranging from 0 to 50 micrograms/ml, however, the suppression of proteolytic activity and total protein in the culture supernate was seen even at 1 micrograms/ml of EM concentration. The degree of suppression was inversely proportional to EM concentration. This phenomenon was also seen in the substitution of CP for EM. All extracellular proteins separated on SDS-PAGE decreased the amount as increasing EM in the culture media. These results suggested that EM inhibited the production of not only protease including elastase, but also any other extracellular proteins including well known pathogenic factors such as exotoxin A and phospholipase C.
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PMID:[Influence of low level antibiotics on Pseudomonas aeruginosa]. 190 12

NADPH oxidase is a superoxide-generating, membrane-bound complex activated in stimulated phagocytes or in a reconstituted system consisting of membranes, cytosolic components and arachidonate or SDS. To delineate mechanism of oxidase activation in the cell-free system, hydrolysis of phosphoinositides in the combined membrane-cytosol oxidase mixture was investigated. Arachidonate promoted hydrolysis of membrane-[3H]-phosphatidylinositol by cytosolic phospholipase C. PI hydrolysis was similarly supported by other unsaturated fatty acids and by SDS. Unlike activation of the NADPH oxidase, PI hydrolysis required the presence of calcium ions. Implications of these findings to the mechanism of NADPH oxidase activation are discussed.
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PMID:Arachidonate supports hydrolysis of phosphatidylinositol by neutrophil cytosolic phospholipase C: relation to NADPH oxidase. 190 42

In bull seminal plasma 5'-nucleotidase is present in heterogeneous forms. The heterogeneity is abolished by treatment of bull seminal plasma with the detergent sodium cholate. The purified enzyme, which is a glycoprotein, shows an apparent molecular mass of 160 kDa on gel filtration in the presence of 50 mmol sodium cholate and an apparent molecular mass of 72 kDa upon SDS/polyacrylamide-gel electrophoresis. The 5'-nucleotidase of bull seminal plasma is a metalloprotein containing 2 zinc ions per molecule of dimeric protein. The removal of the two zinc ions from the protein results in a completely inactive apoenzyme. The substitution of the endogenous zinc with Co(II) Cu(II) produces a holoenzyme which is slightly activated in the case of Co(II), whereas, in the case of Cu(II) only 65% of the initial activity is recovered. The enzyme has a covalently attached glycosyl-phosphatidylinositol moiety which can be removed by treatment with phosphatidylinositol-specific phospholipase C. ESR studies have indicated a radius of 35 A for the protein and that Cu(II) binds to the metal-free enzyme to a site in which sulphur donors can be excluded.
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PMID:5'-Nucleotidase from bull seminal plasma. Biochemical and biophysical aspects. 196 12

Monoclonal antibody (MAb) D612 recognizes an antigen expressed on the cell surface of normal and malignant gastrointestinal epithelium. It is a murine IgG2a/kappa which has been previously shown to mediate killing of human colon carcinoma cells using human effector cells (which could be enhanced in the presence of interleukin-2). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses of MAb D612 immunoprecipitates of extracts of L-[35S]methionine-, L-[3H]leucine-, and D-[3H]glucosamine-labeled human colon carcinoma cells showed that the D612 antigen is a Mr 48,000 glycoprotein. Similar estimates of molecular mass were obtained from SDS-PAGE analyses of MAb D612 immuno-precipitates of radioiodinated extracts of surgically resected colon carcinoma and adjacent normal colonic mucosa. D612 antigen was not detectable in immunoprecipitates of supernatant media from radiolabeled cell cultures, suggesting that the antigen is not readily shed from the surface of cultured cells. The D612 antigen was shown to be clearly distinct from previously described gastrointestinal carcinoma-associated glycoproteins: the D612 antigen shows a migration pattern of SDS-PAGE distinct from those of the antigens recognized by MAbs KS1/4 and GA733, and reciprocal immunodepletion analyses of D-[3H]glucosamine-labeled colon carcinoma cells utilizing MAbs D612 and GA733 revealed no cross-reactivity between these antibodies. Similarly, competitive binding studies between MAbs 17-1A and KS1/4 and MAb D612 revealed no similarity between the epitopes recognized by MAb D612 and MAbs 17-1A and KS1/4. MAbs D612 and 17-1A were also titered in immunoperoxidase staining assays on serial frozen sections of normal and malignant colon. MAb D612 showed a higher titer of immunostaining reactivity with both normal and malignant colon than did MAb 17-1A. MAb D612 showed roughly equivalent immunostaining titers against normal and malignant colon; whereas MAb 17-1A showed higher titer of immunostaining reactivity against the normal colon tissue than against the malignant colon. Flow cytometric analysis of phosphatidylinositol-specific phospholipase C-treated colon carcinoma cells revealed no loss of D612 antigen from the cell surface, suggesting that the mechanisms of attachment of the D612 antigen to the cell surface does not involve linkage to a phosphatidylinositol glycan.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Characterization of the colorectal carcinoma-associated antigen defined by monoclonal antibody D612. 198 33

Polyclonal IgG, prepared to a purified bovine cell surface sialoglycopeptide (SGP) inhibitor of cell division, was used to identify an antigenically related molecule on the surface of Swiss 3T3 cells. SDS-PAGE and Western analyses showed that the anti-SGP antibody was monospecific and primarily recognized a 66-kDA protein of 3T3 cell membranes. Treatment of intact 3T3 cells or 3T3 cell membranes with either broad and phosphatidylinositol-specific phospholipase C enzymes suggested that the antigenic material most likely existed as an integral membrane molecule, or associated as a multimeric complex, and was not anchored at the cell surface by a phospholipid. The addition of anti-SGP IgG to 3T3 cell monolayer cultures was shown to promote cell division, suggesting a regulatory function for the membrane-associated molecule.
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PMID:Identification of a cell surface component of Swiss 3T3 cells associated with an inhibition of cell division. 207 Aug 22

AG-1 is a monoclonal antibody that binds to human platelets and causes aggregation and secretion. Previous work has established that these responses result from phospholipase C-mediated hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2). To determine the mechanism by which this ligand induces signals for platelet activation, we performed a series of experiments examining the platelet binding site for AG-1. AG-1 immunoprecipitates from radioiodinated human platelet plasma membranes a protein of Mr 21,000. AG-1 immunoprecipitated proteins separated by SDS-PAGE, transferred to nitrocellulose, and incubated with [alpha 32P]GTP demonstrate binding of the radiolabeled GTP to the Mr 21,000 protein. A 100-fold molar excess of unlabeled GTP inhibits completely this binding of [alpha 32P]GTP. These results indicate that AG-1 interacts with a low Mr GTP-binding protein on the surface of platelets and suggests that either the protein recognized by AG-1 or a coprecipitating molecule of similar Mr is a low Mr GTP-binding protein that may function in platelet extracellular signal transduction.
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PMID:The monoclonal antibody AG-1, a potent stimulator of human platelets, interacts with a low molecular weight GTP-binding protein. 212 Nov 39

1. Guanosine 5'-[gamma-thio]triphosphate (GTP[S]) stimulated by 50% the rate of release of [3H]choline and [3H]phosphorylcholine in rat liver plasma membranes labelled with [3H]choline. About 70% of the radioactivity released in the presence of GTP[S] was [3H]choline and 30% was [3H]phosphorylcholine. 2. The hydrolysis of phosphorylcholine to choline and the conversion of choline to phosphorylcholine did not contribute to the formation of [3H]choline and [3H]phosphorylcholine respectively. 3. The release of [3H]choline from membranes was inhibited by low concentrations of SDS or Triton X-100. Considerably higher concentrations of the detergents were required to inhibit the release of [3H]phosphorylcholine. 4. Guanosine 5'-[beta gamma-imido]triphosphate and guanosine 5'-[alpha beta-methylene]triphosphate, but not adenosine 5'-[gamma-thio]-triphosphate, stimulated [3H]choline release to the same extent as did GTP[S]. The GTP[S]-stimulated [3H]choline release was inhibited by guanosine 5'-[beta-thio]diphosphate, GDP and GTP but not by GMP. 5. It is concluded that, in rat liver plasma membranes, (a) GTP[S]-stimulated hydrolysis of phosphatidylcholine is catalysed predominantly by phospholipase D with some contribution from phospholipase C, and (b) the stimulation of phosphatidylcholine hydrolysis by GTP[s] occurs via a GTP-binding regulatory protein.
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PMID:The roles of phospholipase D and a GTP-binding protein in guanosine 5'-[gamma-thio]triphosphate-stimulated hydrolysis of phosphatidylcholine in rat liver plasma membranes. 212 11

Alkaline phosphatase (ALP) activity has been demonstrated in periodontal ligament (PDL). On the basis of electron microscopic study, distribution of the enzyme in PDL tissue has also been indicated not only as a cell associated activity but also as an extracellular matrix associated activity. This study is concerned with the purification and characterization of the enzyme obtained from bovine PDL tissue. Purification of ALP extracted from the tissue included solubilization with 10 mM Tris-HCl buffer, pH 7.4, containing 0.2 mM MgCl2 and 0.1% Nonidet P-40 and fractionation by sequential chromatography utilizing DEAE-sephacel, Sepharose CL-6B and concanavalin A Sepharose 4B. Purity was established by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This was followed by staining for ALP activity first with 2 mM beta-naphthyl acid phosphate and 1 mM Fast Blue BB Salt and then the protein with Coomassie Brilliant Blue. SDS-PAGE of the crude enzyme preparations gave a broad band with apparent molecular weight of 110,000-130,000 dalton. ALP activities were separated into two major peaks using Sepharose CL-6B chromatography. The void volume peak showed a purified form of 110,000 dalton ALP (110K ALP) while the second peak contained 120,000-130,000 dalton ALP (120-130K ALP) and other proteins. Sequentially, 120-130K ALP was purified by chromatography on concanavalin A Sepharose 4B. A polyclonal antibody was raised against purified bovine PDL 110K ALP in a rabbit. Immunodiffusion analysis showed that a polyclonal antibody against 110K ALP recognized 120-130K ALP. Analytical affinity chromatography on concanavalin A Sepharose 4B indicated that 110K ALP and 120-130K ALP had distinct affinity to the column which may depend upon the sugar chain structure. Digestion of 110K ALP with phosphatidylinositol-specific phospholipase C affected electrophoretic mobility but 120-130K ALP had no effect. It is suggested that 110K ALP is attached to a cell membrane anchored by a phosphatidylinositol glycan. In conclusion, bovine PDL contains two types of alkaline phosphatase i.e. 110K ALP and 120-130K ALP. Both ALPs are immunologically related although they have different sugar chain moieties. Furthermore, 110K ALP has a membrane anchoring domain. These results suggest that 110K ALP would be localized on the surface of the cell membrane and 120-130K ALP may associated with the extracellular matrix.
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PMID:[Purification and characterization of alkaline phosphatase obtained from bovine periodontal ligament]. 213 40

FcRIII is not present on peripheral blood monocytes, but becomes expressed upon culturing and can be demonstrated on tissue macrophages. We studied the expression of FcRIII of cultured monocytes in detail and compared its structure with FcRIII of neutrophils and NK cells. The cell density of FcRIII reached a plateau within 3 days of culturing. During that time, the expression of FcRI and FcRIIa, also present on monocytes, did not change significantly. FcRIII on cultured monocytes lacked, as did NK cell FcRIII, the NA1-allotypic variant of the NA system present on the neutrophil FcRIII. Studies with glycosyl-phosphatidyl-inositol-specific phospholipase C and analysis of cells of patients with paroxysmal nocturnal hemoglobinuria revealed that FcRIII on cultured monocytes is not anchored by phosphatidyl-inositol-glycan in the cell membrane. Similarly, FcRIII on NK cells was resistant to glycosyl-phosphatidyl-inositol-specific phospholipase C treatment, suggesting that NK cell FcRIII is also not anchored by a phosphatidyl-inositol-glycan moiety, in contrast to neutrophil FcRIII. Analysis by SDS-PAGE showed that the FcRIII of cultured monocytes had a similar mobility as the FcRIII on NK cells, but was clearly distinct from neutrophil FcRIII. Treatment with N-glycanase showed that the protein backbone of deglycosylated FcRIII of cultured monocytes was similar to that of FcRIII of NK cells, but deglycosylated neutrophil FcRIII was different. Specific blocking of FcRIII of cultured monocytes with an anti-FcRIII mAb did not reduced the lytic action of the cultured monocytes towards sensitized erythrocytes. However, FcRIII was modulated from the cell surface by incubation with sensitized E, whereas non-FcR Ag were not. These findings indicate that FcRIII is involved in binding of immune complexes, but does not act as a trigger molecule for extracellular lysis of sensitized E.
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PMID:The Fc-receptor III of cultured human monocytes. Structural similarity with FcRIII of natural killer cells and role in the extracellular lysis of sensitized erythrocytes. 213 96

Mo3 is an activation Ag expressed by human monocytic cells after stimulation in vitro by PMA, LPS, certain cytokines, and muramyl dipeptide. The structural characterization of Mo3 has been made possible by the development of a mAb (anti-Mo3f) that immunoprecipitates Mo3 from Nonidet P-40 lysates of radiolabeled PMA-stimulated U-937 cells and LPS-activated monocytes. On SDS-PAGE (nonreducing conditions) of anti-Mo3f immunoprecipitates, U-937 Mo3 is a single broad band of 39 to 66 kDa, whereas monocyte Mo3 is smaller with an apparent molecular mass of 32 to 56 kDa. Under reducing conditions, there is an increase in the m.w. of both species of Mo3 suggesting the existence of internal disulfide bonds. Mo3 is a glycoprotein with carbohydrate of the N-linked complex type as evidence by a reduction in m.w. by 40 to 50% after treatment with endoglycosidase F or N-glycanase; neuraminidase treatment produces a 3-kDa reduction in m.w. Deglycosylated Mo3 isolated from U-937 and monocytes have similar m.w. suggesting that the molecular heterogeneity of the native Mo3 may be due to differences in glycosylation. Mo3 is sensitive to phosphatidylinositol-specific phospholipase C with the release of native Mo3 from the surface of PMA-stimulated U-937 cells. These results indicate that Mo3 is a member of the glycosylphosphatidylinositol-linked family of surface glycoproteins.
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PMID:A structural characterization of the Mo3 activation antigen expressed on the plasma membrane of human mononuclear phagocytes. 213 44


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