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

---

Query: EC:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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)
...
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.
...
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.
...
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.
...
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.
...
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.
...
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.
...
PMID:A structural characterization of the Mo3 activation antigen expressed on the plasma membrane of human mononuclear phagocytes. 213 44

Aminopeptidase P (EC 3.4.11.9) was solubilized from pig kidney membranes with bacterial phosphatidylinositol-specific phospholipase C (PI-PLC) and then purified by a combination of anion-exchange and hydrophobic-interaction chromatographies. Contaminating peptidase activities were removed by selective affinity chromatography. The purified enzyme was apparently homogeneous on SDS/PAGE with an Mr of 91,000. Enzymic deglycosylation revealed that aminopeptidase P is a glycoprotein, with up to 25% by weight of the protein being due to the presence of N-linked sugars. The phospholipase-solubilized aminopeptidase P was recognized by an antiserum to the cross-reacting determinant (CRD) characteristic of the glycosyl-phosphatidylinositol anchor. This recognition was abolished by mild acid treatment or deamination with HNO2, indicating that the CRD was due exclusively to the inositol 1,2-cyclic phosphate ring epitope generated by the action of PI-PLC. The activity of aminopeptidase P was inhibited by chelating agents and was stimulated by Mn2+ or Co2+ ions, confirming the metallo-enzyme nature of this peptidase. Selective inhibitors of other aminopeptidases (actinonin, amastatin, bestatin and puromycin) had little or no inhibitory effect.
...
PMID:Purification and characterization of pig kidney aminopeptidase P. A glycosyl-phosphatidylinositol-anchored ectoenzyme. 213 78

The mechanisms of endothelin-1 (ET) actions were investigated in cultured rat aortic vascular smooth muscle A-10 cells. The A-10 cells have a single class of high affinity binding sites for ET with an apparent Mr of 65,000-75,000 on SDS-PAGE. Stimulation of cells with ET induces mobilization of Ca2+ from both intra- and extracellular pools to produce a biphasic increase in cytoplasmic free Ca2+ concentration. ET increases cellular levels of inositol trisphosphate and 1,2-diacylglycerol, indicating activation of phospholipase C by ET. ET stimulates production of inositol phosphates in membranes prepared from A-10 cells in the presence of guanosine 5'-O-(thiotriphosphate) (GTP gamma S), but not in its absence. Further, specific binding of 125I-labeled ET to A-10 cell membranes is shown to be inhibited by GTP gamma S in a dose-dependent manner. Treatment of A-10 cells with pertussis toxin induces ADP-ribosylation of a 41,000-D membrane protein but fails to block the ET-induced increases in inositol phosphate production and Ca2+ mobilization. These results indicate that the receptor for ET is coupled to phospholipase C via a guanine nucleotide-binding regulatory protein which is distinct from the pertussis toxin substrate in A-10 cells.
...
PMID:Endothelin receptor is coupled to phospholipase C via a pertussis toxin-insensitive guanine nucleotide-binding regulatory protein in vascular smooth muscle cells. 215 22

A human platelet cytosolic phosphoinositide-specific phospholipase C, one of four PLC activity peaks separated by column chromatographies, designated as cPLC-I, was purified to homogeneity. The cPLC-I exhibited an apparent Mr of 145 kDa by SDS-polyacrylamide gel electrophoresis and was immunologically identified to be PLC-gamma 2. It hydrolyzed PI and PIP2 at optimum pH of 5.5-6.0. Deoxycholate and cholate inhibited the enzyme activity to hydrolyze two substrates. Calcium was required to obtain the maximal activity for PI- and PIP2-hydrolysis at concentration of 10(-3) M and 10(-5) M, respectively. Hg2+ (1 microM) inhibited strongly the enzyme activity.
...
PMID:Purification and characterization of a cytosolic phosphoinositide-phospholipase C (gamma 2-type) from human platelets. 215 3


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---