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)

The Rho(D) antigen of red cell membranes was solubilized using ethylene-diamine tetraacetic acid (EDTA) and 2-mercaptoethanol. The solubilized antigen was partially separated from other solubilized membrane components using molecular filtration. The antigen was treated with various enzymes to learn some of the chemical characteristics. It was found that the activity of the antigen, as measured by hemagglutination inhibition, was not affected by bee venom phospholipase A, Clostridium welchii phospholipase C, calf-intestinal alkaline phosphatase, Vibrio cholerae neuraminidase, pig kidney leucine aminopeptidase, bovine pancreatic carboxypeptidase A, and pig pancreatic carboxypeptidase B. However, the proteolytic enzymes, pronase, trypsin, chymotrypsin and papain, did destroy Rho(D) activity as measured by hemagglutination inhibition. These results indicate that protein is an important part of the active determinant of the Rho(D) antigen. The experiments by other investigators have shown that lipid is important to maintain the Rho(D) activity in the intact membrane; lipid probably helps to maintain the structural conformation of the Rho(D) molecule in its natural environment. The solubilized Rho(D) molecules are apparently not dependent on lipid for their Rho(D) activity.
 ...
PMID:Studies on the characterization of the Rho(D) antigen. 10 79

Staphylococcal alpha-toxin (alpha-toxin) was incubated with 3T3 or SV40-virus transformed mouse 3T3 fibroblasts during 2 hrs at room temperature. This resulted in about a two-fold increase in the hemolytic activity of alpha-toxin toward rabbit RBC. The concentration of alpha-toxin causing 50% hemolysis of rabbit RBC was lowered from about 120 ng/ml to about 65 ng/ml. Release of 86Rb from labeled RBC and isolated rabbit vagus nerves also occured at lower concentrations of alpha-toxin after preincubation with fibroblasts. The enhancement of hemolytic activity of alpha-toxin was still exerted by cultured fibroblasts preheated to 56 degrees C, but fibroblasts exposed to 100 degrees C were ineffective. The hemolytic activity of alpha-toxin toward rabbit RBC was also slightly enhanced by leucine aminopeptidase (5--20 microgram/ml) and aminopeptidase M (30--300 IU/ml).
 ...
PMID:Enhancement of hemolytic and cytotoxic activity of staphylococcal alpha-toxin in vitro by incubation with cultured fibroblasts. Brief communication. 66 79

1. Liver plasma membranes originating from the sinusoidal, lateral and canalicular surface domains of hepatocytes were covalently labelled with sulpho-N-hydroxysuccinamide-biotin. After solubilization in Triton X-114, treatment with a phosphatidylinositol-specific phospholipase C (PI-PLC), two-phase partitioning and 125I-streptavidin labelling of the proteins resolved by PAGE, six major polypeptides (molecular masses 110, 85, 70, 55, 38 and 35 kDa) were shown to be anchored in bile canalicular membrane vesicles by a glycosyl-phosphatidylinositol (G-PI) 'tail'. 2. Permeabilized 'early' and 'late' endocytic vesicles isolated from liver were also examined. Two polypeptides (110 and 35 kDa) were shown to be anchored by a G-PI tail in 'late' endocytic vesicles. 3. Analysis of marker enzymes in bile-canalicular vesicles treated with PI-PLC showed that 5'-nucleotidase and alkaline phosphatase, but not leucine aminopeptidase and ecto-Ca2(+)-ATPase activities were released from the membrane. A low release and recovery of alkaline phosphodiesterase activity was noted. The cleavage from the membrane of 5'-nucleotidase as a 70 kDa polypeptide was confirmed by Western blotting using an antibody to this enzyme. 4. Antibodies raised to proteins released from bile-canalicular vesicles by PI-PLC treatment, and purified by partitioning in aqueous and Triton X-114 phases, localized to the bile canaliculi in thin liver sections. Antibodies to proteins not hydrolysed by this treatment stained by immunofluorescence the sinusoidal and canalicular surface regions of hepatocytes. 5. Antibodies generated to proteins cleaved by PI-PLC treatment of canalicular vesicles were shown to identify, by Western blotting, a major 110 kDa polypeptide in these vesicles. Two polypeptides (55 and 38 kDa) were detected in MDCK and HepG-2 cultured cells. 6. Since two of the six G-PI-anchored proteins targeted to the bile-canalicular plasma membrane were also detected in 'late' endocytic vesicles, the results suggest that a junction where exocytic and endocytic traffic routes meet occurs in a 'late' endocytic compartment.
 ...
PMID:Priority targeting of glycosyl-phosphatidylinositol-anchored proteins to the bile-canalicular (apical) plasma membrane of hepatocytes. Involvement of 'late' endosomes. 217 97

The release of plasma-membrane-bound enzymes by phosphatidylinositol-specific phospholipase C obtained from Bacillus thuringiensis was investigated. Among the ectoenzymes of plasma membrane tested, alkaline phosphodiesterase I was released markedly from rat kidney cortex slices, in addition to alkaline phosphatase and 5'-nucleotidase. Other membrane-bound enzymes; alanine aminopeptidase, leucine aminopeptidase, dipeptidyl peptidase, leucine aminopeptidase, dipeptidyl peptidase IV, esterase and gamma-glutamyl transpeptidase could not be liberated from the treated slices. Alkaline phosphodiesterase I was released linearly from rat kidney slices with the concentration of phosphatidylinositol-specific phospholipase C, but little enzyme was released from rat liver slices. Alkaline phosphodiesterase I separated from kidney tissue with n-butanol still retained phosphatidylinositol and was transformed into a lower molecular weight form by phosphatidylinositol-specific phospholipase C. This suggests an important function for phosphatidylinositol in the binding of alkaline phosphodiesterase I to the plasma membrane of rat kidney cells. The alkaline phosphodiesterase I released from rat kidney had a molecular weight of about 240,000 and an isoelectric point (pI) of 5.4. The enzyme hydrolyzed the phosphodiester linkage of p-nitrophenyl-thymidine 5'-monophosphate at pH 8.9 and had a Km value of 0.3 mM. The enzyme was activated by Mg2+ and Ca2+, but was inhibited by EDTA. Strong inhibition took place on the addition of adenosine 5'-phosphosulfate or the nucleotide pyrophosphates, i.e., UDP-galactose and alpha, beta-methylene ATP.
 ...
PMID:Release of alkaline phosphodiesterase I from rat kidney plasma membrane produced by the phosphatidylinositol-specific phospholipase C of Bacillus thuringiensis. 609 28

Treatment of liver plasma membranes with trypsin at low concentrations (1 to 2 microgram/mg of protein) caused at 3- to 4-fold increase in alpha-specific [3H]epinephrine binding. The change was due to an increase in the number of high affinity binding sites, with no change in the dissociation constant. With increasing trypsin concentrations, the dissociation constant was decreased and there was a progressive loss of binding. Elastase, papain, and thermolysin caused similar effects, whereas the thrombin, leucine aminopeptidase, phospholipase A2, phospholipase C, phospholipase D, and detergents did not cause an increase in [EH]epinephrine binding. The increase in epinephrine high affinity binding sites was correlated with a loss of high affinity [3H]-dihydroergocryptine binding sites which also bind [3H]epinephrine with low affinity (El-Refai, M. F., Blackmore, P. F., and Exton, J. H. (1979) J. Biol. Chem. 254, 4375-4386). Incubation of membranes with the alpha blockers dihydroergocryptine (50 nM) and phenoxybenzamine (20 nM) prior to protease treatment diminished the increase in [3H]epinephrine binding induced by trypsin (1.5 microgram/mg). The concentration dependence and time course of trypsin actions on 70 nM [3H]epinephrine binding and 10 nM [3H]dihydroergocryptine binding are consistent with a trypsin-mediated conversion of low affinity epinephrine binding sites to high affinity epinephrine binding sites.
 ...
PMID:Effects of trypsin on binding of [3H]epinephrine and [3H]-dihydroergocryptine to rat liver plasma membranes. Evidence for interconversion of binding sites. 624 49

Membrane proteins can be attached to the plasma membrane in several ways. Recently, a mechanism has been described, by which a number of cell surface proteins are anchored to the exoplasmic side of the plasma membrane by covalent linkage to glycosyl-phosphatidylinositol (GPI). The growth properties of renal epithelial cells in tissue culture enable free access to apical cell surface and brush border membrane proteins. To study the nature of membrane anchoring of apical plasma membrane enzymes in cultured renal epithelial cells, confluent LLC-PK1, OK, NRK, and MDCK epithelia were treated in tissue culture dishes with bacterial phosphatidylinositol-specific phospholipase C (PI-PLC), and the PI-PLC-specific release into the tissue culture medium of the apical membrane enzymes alkaline phosphatase (AP), gamma-glutamyl transpeptidase, leucine aminopeptidase, trehalase, and maltase was determined. Of the five enzymes tested, AP and trehalase, already described as GPI-anchored membrane proteins, were specifically released by PI-PLC from intact cell monolayers. Of the four cell lines investigated, LLC-PK1 cells express AP and trehalase which were released by PI-PLC. In OK cells, which lack AP activity, only trehalase was found to have PI-PLC-releaseable enzyme activity. MDCK cells, on the other hand, express AP activity, releaseable by PI-PLC, but no trehalase activity. In studies on the time course of synthesis and reinsertion of AP into the apical membrane of LLC-PK1 cells after removal by PI-PLC, a 60% recovery of AP activity was obtained only after 7 days. Analysis of protein release by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of culture supernatants after surface labeling with biotin and subsequent Western blotting with streptavidin revealed four protein bands at approximately 130, 90, 30, and 20 kD in LLC-PK1 cells and five GPI-anchored proteins at 110, 85, 65, 40, and 26 kD in OK cultures. The finding of a PI-PLC-specific release of apical membrane enzymes from renal tubular cell lines of different species (pig, opossum, rat, and dog) and of different nephron origin indicates a high conservation of the GPI anchor of renal brush border membrane proteins and further proves the high degree of differentiation retained by the cell lines in tissue culture. In addition, this method may provide a possible tool for isolating GPI-anchored apical membrane proteins from intact epithelial monolayer cultures.
 ...
PMID:Selective release of apical membrane enzymes from cultured renal epithelia by phosphatidylinositol-specific phospholipase C. 750 39

Membrane-bound liver alkaline phosphatase (Mem-LiALP, EC 3.1.3.1) is a high-molecular-mass liver alkaline phosphatase (ALP) present in metastatic, infiltrative and cholestatic liver disease. Shedding of hepatocyte plasma membrane fragments (LiPMF) is thought to be responsible for the appearance of Mem-LiALP in the circulation. Several other membrane-bound enzymes, such as gamma-glutamyltransferase (gamma-GT), leucine aminopeptidase (LAP), and 5'-nucleotidase (5'-Nu) are present in the membrane of the shedded LiPMF. By means of immunohistochemical and immunoassay procedures, we presently show that AD-1, a specific monoclonal antibody originally produced against Mem-LiALP, reacts with LAP, a constituent of the human liver plasma membrane. Using AD-1 as an immunosorbant, we isolated circulating LiPMF from cholestatic sera to a high level of purity and separated it from other high-molecular-mass material, such as liver ALP or similar lipoprotein-X complexes. These purified membrane fragments retained their biochemical characteristics. Glycosyl-phosphatidylinositol anchor bearing liver ALP (Anch-LiALP) could be released from the LiPMF by Triton X-100. Whereas ALP was released upon treatment of AD-1 purified LiPMF with phospholipase C, phospholipase D only cleaved the glycosyl-phosphatidylinositol anchor following detergent solubilization of the enzyme. Serum LiPMF from patients with different kinds of cholestatic liver disease were bound onto AD-1 coated nitrocellulose disks and the activity of four membrane-bound enzymes (LAP, ALP, 5'Nu, gamma-GT) was analyzed. A considerable interindividual variation of enzyme activities was observed, suggesting some heterogeneity in the membrane composition of these fragments.
 ...
PMID:Purification of circulating liver plasma membrane fragments using a monoclonal antileucine aminopeptidase antibody. 861 23

The binary toxin (Bin) from Bacillus sphaericus crystals specifically binds to soluble midgut brush border membrane proteins from Culex pipiens larvae. A single 60 kDa midgut membrane protein is identified as the binding protein. This protein is anchored in the mosquito midgut membrane via a glycosyl-phosphatidylinositol (GPI) anchor, and is partially released by phosphatidylinositol specific-phospholipase C (PI-PLC). Fractionation of soluble proteins by anion exchange chromatography indicates that the binding protein does not co-elute with leucine aminopeptidase activity. After partial purification, the sequences of internal amino acid fragments of the 60 kDa protein were determined. The peptide sequences were compared with data in GenBank, and showed a very high degree of similarity with enzymes belonging to the alpha-amylase family. Further enzymatic investigation showed that the receptor of the Bin toxin in C. pipiens larval midgut may be an alpha-glucosidase.
 ...
PMID:Identification of the receptor for Bacillus sphaericus crystal toxin in the brush border membrane of the mosquito Culex pipiens (Diptera: Culicidae). 1045 23