Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

MCA44 is a mAb with the capacity to sensitize neuraminidase-treated guinea pig E for hemolysis by homologous guinea pig C, and the Fab fragments of this mAb could also sensitize guinea pig E interfering with the function of a membrane inhibitor of C on guinea pig E. Using an immunosorbent column to which MCA44 was coupled, the antigenic molecule termed 44Ag was purified from the glycoprotein fraction extracted from E membranes. C intermediate sheep E treated with guinea pig C1 and C4 after sensitization with Ab (EAC14b cells) lost the ability to generate C3 convertase with C2 after incubation with 44Ag. Treatment of guinea pig E and PBL with phosphatidyl-inositol specific phospholipase C (PIPLC) partially removed 44Ag, as determined by flow cytometric analysis after immunofluorescence staining with MCA44. However, 125I-labeled 44Ag adsorbed to human E was efficiently removed by PIPLC treatment with a slight reduction in M(r). The 44Ag purified on an immunosorbent column showed three bands on SDS-PAGE. However, partial N-terminal amino acid sequences of the 55-kDa, 70-kDa, and 88-kDa bands under nonreducing conditions were identical and the sequence was 55% homologous to the N-terminal sequence of human decay accelerating factor (CD55). Intracutaneous administration of MCA44 or its F(ab')2 fragment resulted in increased capillary permeability, even after 3 days, as determined by the appearance of Evans blue spots after i.v. administration of the dye. Because control Abs including anti-class I-MHC did not cause such increased capillary permeability, the increase in permeability caused by MCA44 was likely induced by blocking the function of 44Ag in vivo, indicating a crucial role for these molecules in preventing over-activation of C at the site.
 ...
PMID:A monoclonal antibody that blocks the complement regulatory activity of guinea pig erythrocytes and characterization of the antigen involved as guinea pig decay-accelerating factor. 753 42

Immunohistochemical and/or indirect immunofluorescence analysis with monoclonal antibody (MAb) H19 demonstrated the expression of protectin (CD59) in 54 surgically removed metastatic melanoma lesions and on 8 out of 12 melanoma cell lines. CD59 expression had a low degree of intra- and intertumor heterogeneity. SDS-PAGE analysis showed that the molecular weight of CD59 expressed on melanoma cells is about 20 kDa. Treatment of melanoma cells with 5U/ml of phosphatidylinositol-specific phospholipase C completely abolished cell-surface expression of CD59. Interferon-gamma and/or tumor necrosis factor-alpha or phorbol 12-myristate 13-acetate neither modulated the expression of CD59 by melanoma cells nor influenced the amounts of CD59-specific mRNA. F(ab')2 fragments of anti-CD59 MAb YTH53. I did not inhibit the lysis of melanoma cells by allogeneic natural killer (NK) cells or lymphokine-activated killer (LAK) cells. In contrast, the whole Ig molecule of MAb HI9 or YTH53.I significantly (p < 0.05) enhanced NK-cell-mediated lysis of melanoma cells, suggesting the induction of antibody-dependent cell-mediated cytotoxicity. Lastly, masking of CD59 by MAb YTH53.I or its F(ab')2 fragments significantly (p < 0.05) enhanced, in a dose-dependent fashion, the lysis of anti-GD3-sensitized melanoma cells by homologous complement. These data demonstrate that CD59 expressed by human melanoma cells might regulate host-tumor interaction by protecting neoplastic cells from complement-mediated lysis.
 ...
PMID:Expression of protectin (CD59) in human melanoma and its functional role in cell- and complement-mediated cytotoxicity. 753 80

A PCR-based strategy has been used to isolate a full length cDNA encoding a phosphatidylinositol-specific phospholipase C from a sized cDNA squid (Loligo forbesi) retinal library. The predicted protein sequence contains 875 amino acids, with calculated M(r) 98,181, and has marked similarity with PLC beta-isoforms, including conservation of the 'X' and 'Y' regions. It is unique in having a major C-terminal truncation. A major protein of apparent M(r) 120,000 estimated by SDS-PAGE has been isolated from squid photoreceptors and identified by partial protein sequence analysis to correspond to the protein sequence predicted from the cDNA clone. This protein has been shown to hydrolyse phosphatidylinositol 4,5-bisphosphate. It is not yet clear whether this represents the major light-activated PLC in squid vision.
 ...
PMID:A beta-subclass phosphatidylinositol-specific phospholipase C from squid (Loligo forbesi) photoreceptors exhibiting a truncated C-terminus. 755 77

Clonal BHK cells permanently transfected with the metabotropic glutamate receptor 1 alpha (mGluR1 alpha), which is coupled to phospholipase C, were used to study the phosphorylation state of the receptor. Cells were labelled with 32PO4(3-), lysed, the receptor immunoprecipitated with specific anti-peptide antibodies and the immunoprecipitates analysed by SDS-PAGE followed by autoradiography. A significant basal level of receptor phosphorylation was observed which was rapidly and transiently increased in response to agonist activation of the receptor. This agonist effect was found to be dose dependent with a rapid time course and could be abolished by the specific PKC inhibitor Ro318220, suggesting that PKC was responsible for the agonist mediated phosphorylation of the receptor.
 ...
PMID:Rapid agonist mediated phosphorylation of the metabotropic glutamate receptor 1 alpha by protein kinase C in permanently transfected BHK cells. 760 28

A cytoskeletal fraction of porcine tracheal smooth muscle (PTSM) was found to contain > 90% of total cellular aldolase (fructose 1,6-bisphosphate aldolase, EC 4.1.2.13) activity. PTSM aldolase was purified by DEAE and inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) affinity chromatography and found to react with an antibody directed against human aldolase C, but not anti-aldolase A and B. The molecular mass of native aldolase was about 138 kDa (on Sephacryl S-300); SDS-denatured enzyme was 35 kDa (comigrated with rabbit skeletal muscle aldolase). Total cellular aldolase tetramer (aldolase4) content was 34.5 pmol/100 nmol lipid P(i). Ins(1,4,5)P3) binding activity coeluted with aldolase during Sephacryl 300, DEAE, and Ins(1,4,5)P3 affinity chromatography. Ins(1,4,5)P3 bound to purified aldolase (at 0 degree C) in a dose-dependent manner over the range [Ins(1,4,5)P3] 20 nM to 20 microM, with maximal binding of 1 mol of Ins(1,4,5)P3/mol aldolase4 and a Kd of 12-14 microM. Fru(1,6)P2 and Fru(2,6)P2 displaced bound Ins(1,4,5)P3) with a 50% inhibition at 30 and 170 microM, respectively. Ins(1,3,4)P3 (20 microM) and glyceraldehyde 3-phosphate (2 mM) were also potent inhibitors of Ins(1,4,5)P3 binding, but not inositol 4-phosphate or inositol 1,4-bisphosphate (20 microM each). Aldolase-bound Ins(1,4,5)P3 may play a role in phospholipase C-independent increases in free [Ins(1,4,5)P3].
 ...
PMID:Inositol 1,4,5-trisphosphate binding to porcine tracheal smooth muscle aldolase. 765 22

CD59 antigen (CD59) is a glycosylphosphatidylinositol (GPI)-linked membrane glycoprotein which protects human cells from complement-mediated lysis. Here we report the expression of functionally active CD59 in Spodoptera frugiperda insect cells using a baculovirus vector. Recombinant CD59 was expressed abundantly on the surface of the insect cells and protected the cells from lysis by human complement. The protein was released from the cell surface by treatment with phosphatidylinositol-specific phospholipase C, indicating that it was attached to the insect cell membrane via a GPI anchor. The cells also secreted CD59 into the culture medium. Recombinant CD59 was affinity-purified from spent culture medium and from detergent extract of transfected cells. Protein purified from both sources produced multiple bands on SDS/PAGE, all of a lower apparent molecular mass than the human erythrocyte protein. However, N-terminal protein sequencing and deglycosylation studies confirmed that signals for leader peptide cleavage and N-linked glycosylation had been recognized in the insect cells, suggesting that the differences in apparent molecular mass between the native and recombinant proteins were attributable to the extent of glycosylation. Protein derived from both sources was, in part, GPI-anchored as demonstrated by phase-partition studies and incorporation into cells membranes. Incorporated recombinant protein rendered erythrocytes resistant to complement lysis.
 ...
PMID:Expression of the glycosylphosphatidylinositol-linked complement-inhibiting protein CD59 antigen in insect cells using a baculovirus vector. 769 73

Two acetylcholinesterases (AChE) differing in substrate and inhibitor specificities have been characterized in the medical leech (Hirudo medicinalis). A 'spontaneously-soluble' portion of AChE activity (SS-AChE) was recovered from haemolymph and from tissues dilacerated in low-salt buffer. A second portion of AChE activity was obtained after extraction of tissues in low-salt buffer alone or containing 1% Triton X-100 [detergent-soluble (DS-) AChE). Both enzymes were purified to homogeneity by affinity chromatography on edrophonium- and concanavalin A-Sepharose columns. Denaturing SDS/PAGE under reducing conditions gave one band at 30 kDa for purified SS-AChE and 66 kDa for DS-AChE. Sephadex G-200 chromatography indicated a molecular mass of 66 kDa for native SS-AChE and of 130 kDa for DS-AChE. SS-AChE showed a single peak sedimenting at 5.0 S in sucrose gradients with or without Triton X-100, suggesting that it was a hydrophylic monomer (G1). DS-AChE sedimented as a single 6.1-6.5 S peak in the presence of Triton X-100 and aggregated in the absence of detergent. A treatment with phosphatidylinositol-specific phospholipase C suppressed aggregation and gave a 7 S peak. DS-AChE was thus an amphiphilic glycolipid-anchored dimer. Substrate specificities were studied using p-nitrophenyl esters (acetate, propionate and butyrate) and corresponding thiocholine esters as substrates. SS-AChE displayed only limited variations in Km values with charged and uncharged substrates, suggesting a reduced influence of electrostatic interactions in the enzyme substrate affinity. By contrast, DS-AChE displayed higher Km values with uncharged than with charged substrates. SS-AChE was more sensitive to eserine and di-isopropyl fluorophosphate (IC50 5 x 10(-8) and 10(-8) M respectively) than DS-AChE (5 x 10(-7) and 5 x 10(-5) M.
 ...
PMID:Solubilization, molecular forms, purification and substrate specificity of two acetylcholinesterases in the medicinal leech (Hirudo medicinalis). 770 60

The isoenzymic properties of the alkaline phosphatase (ALP) of the gingival crevicular fluid (GCF) were investigated and compared with those in other cells, such as human polymorphonuclear leukocytes (PMNs), and human periodontal ligament cells (PDLs), and with those of three species of periodontopathic bacteria: Porphyromonas gingivalis 381 (P. gingivalis), Prevotella intermedia ATCC25611 (P. intermedia), and Capnocytophaga sputigena ATCC33123 (C. sputigena). The biochemical properties of the isoenzymes were analyzed by the following methods: enzyme assays, inhibition pattern using three chemical inhibitors, 4 to 20% gradient polyacrylamide gel electrophoresis, thermostability, immunological specificity, and phosphatidylinositol-specific phospholipase C (PI-PLC) treatment. The inhibition experiment showed that ALP of the PMNs and PDLs possessed almost the same enzymatic properties of tissue-nonspecific ALP (bone/liver/kidney; TNSALP), and the ALP of the three species of periodontopathic bacteria possessed specific properties that were different from those of TNSALP, intestinal, or placental ALP. The ALP of the GCF was only slightly susceptible to levamisole (1 mM), L-phenylalanine (20 mM), and SDS (1%). An electrophoresis thermostability test demonstrated that the enzyme activity of the GCF was separated into one or two bands. The main heat-labile slow band contained the phosphatidylinositol (PI)-moiety-anchored ALP and possessed immunological specificity against anti-bone type ALP. The minor fast band was heat stable and showed mobility similar to that in P. gingivalis. These results indicated that the ALP of the GCF consisted of several ALP isoenzyme types whose possible origins are considered to be derived from phosphatidylinositol (PI) anchored ALP and periodontopathic bacterial ALP.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Properties of alkaline phosphatase in the gingival crevicular fluid. 779 88

Sera of patients with chronic Chagas' disease (American trypanosomiasis) contain elevated levels of anti-alpha-galactosyl antibodies that are lytic to Trypanosoma cruzi. The T. cruzi trypomastigote F2/3 antigen complex recognized by these antibodies runs as a broad smear on SDS/PAGE [Almeida, Krautz, Krettli and Travassos (1993) J. Clin. Lab. Anal. 7, 307-316]. Treatment of T. cruzi trypomastigote cells with bacterial phosphatidylinositol-specific phospholipase C (PI-PLC) abolished most of their reactivity to chronic Chagas'-disease ((Chagasic, Ch) anti-alpha-galactosyl antibodies (anti-Gal). The F2/3 antigen complex, purified by solvent extraction and hydrophobic-interaction chromatography, contained 60% carbohydrate by weight and substantial amounts of Thr, Ser, Glx, Asx, Gly, Ala and Pro, but relatively few hydrophobic amino acids. The presence of myoinositol, ethanolamine and 1-O-hexadecylglycerol suggested the presence of glycosyl-phosphatidylinositol membrane anchors. This was confirmed by PI-PLC treatment, which rendered the F2/3 molecules hydrophilic and reactive to anti-(cross-reacting determinant) antibodies. The majority of the GlcNAc content of the F2/3 antigens was found at the reducing termini of oligosaccharides in O-glycosidic linkage to Thr residues. These O-linked oligosaccharides could be released by beta-elimination and by mild hydrazinolysis. The smallest released oligosaccharitol that was reactive with the Ch anti-Gal was Gal alpha 1-3Gal beta 1-4GlcNAcol (where GlcNAcol is N-acetyl-glucosaminitol). Several other Gal-containing oligosaccharitols were observed, most of which were branched and contained 4,6-di-O-substituted GlcNAcol at their reducing termini. About half of the total released oligosaccharitols could bind to immobilized Ch anti-Gal, but none of them bound to the anti-Gal isolated from normal human sera. These data suggest that the specificities of the Ch anti-Gal are quite different from the natural anti-Gal isolated from normal human sera. Therefore, these novel T. cruzi O-linked oligosaccharides are highly immunogenic under the conditions of natural infection and are the targets for lytic Ch anti-Gal.
 ...
PMID:Lytic anti-alpha-galactosyl antibodies from patients with chronic Chagas' disease recognize novel O-linked oligosaccharides on mucin-like glycosyl-phosphatidylinositol-anchored glycoproteins of Trypanosoma cruzi. 781 83

A soluble form of urokinase-binding protein has been isolated from the human fibrosarcoma cell line HT-1080 and cell lines derived from it. Conditioned media of these cells were collected after overnight incubation under serum-free conditions, and were concentrated and passed through a column of Sepharose 4B to which high-molecular-weight urokinase had been attached. After thorough washing, a polypeptide could be eluted from the column with 1 M acetic acid. This material appeared to be a single band of approximately 60 kDa on SDS polyacrylamide gel. It cross-reacted with commercial antibodies made against urokinase receptor, and could be chemically cross-linked to the amino terminal fragment of urokinase. This material was similar to the urokinase receptor that was cleaved from HT-1080 cells by means of phosphatidylinositol-specific phospholipase C.
 ...
PMID:Soluble urokinase receptor from fibrosarcoma HT-1080 cells. 784 1


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