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)

Insulin action is thought to be mediated by an inositol-, glucosamine- and galactose-containing oligosaccharide liberated by phosphodiesterase hydrolysis of a glycosyl-phosphatidylinositol. This oligosaccharide inhibits insulin biosynthesis and secretion in pancreatic islets. In the present study, two main glycolipids (peak I and II) were resolved by sequential TLC of lipids extracted from islet cells labelled with tritiated glucosamine, galactose or myristate. The two glycolipids displayed comparable sensitivity to beta-galactosidase but differed from one another by their sensitivity to phosphatidylinositol-specific phospholipase C. Moreover, structural heterogeneity within each peak was suggested by their partial resistance to nitrous acid deamination. These findings support the presence in islet cells of glycolipids similar to those currently considered as a possible postreceptor target for insulin in other cell types.
 ...
PMID:Metabolic labelling and partial characterization of glycophospholipids in pancreatic islet cells. 165 34

K1 is a monoclonal antibody that reacts with a cell surface antigen (CAK1) found in human mesothelia and nonmucinous ovarian tumors. In this article, the characteristics of the CAK1 antigen have been examined in detail. Using immunofluorescence microscopy, we have found that the CAK1 signal is removed from the cell surface by treatment with proteases or by phosphatidylinositol-phospholipase C, but not by neuraminidase and beta-galactosidase. The phosphatidylinositol-phospholipase C-released material was found to contain the CAK1 antigen which was detected by a competition radioimmunoassay. The phosphatidylinositol-phospholipase C-released CAK1 antigen was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting and found to be approximately 40 kDa protein. The CAK1-K1 antibody complex remains on the cell surface and is poorly internalized, as shown by an acid wash immunofluorescence internalization assay. An immunotoxin composed of K1 and Lys-PE40, a mutant form of Pseudomonas exotoxin lacking the cell binding domain, was not cytotoxic, supporting the conclusion that the CAK1-K1 antibody complex is not internalized. However, an immunotoxin composed of K1 and native Pseudomonas exotoxin was selectively cytotoxic to cells expressing the CAK1 antigen. This cytotoxicity is due to the fact that domain I of Pseudomonas exotoxin promotes internalization of antigens which are not internalized or bound to antibody alone. Our results suggest that CAK1 is a polypeptide that is expressed on mesothelial cells and many ovarian cancers, and that K1 may be useful as a targeting agent for the immunotherapy of human ovarian cancer.
 ...
PMID:Characterization of the antigen (CAK1) recognized by monoclonal antibody K1 present on ovarian cancers and normal mesothelium. 172 78

We have investigated the topography of a glycosyl-phosphatidylinositol implicated in insulin action by a combination of two complementary methods: (a) chemical labelling with a non-permeable (isethionyl acetimidate) and a permeable (ethyl acetimidate) probe; and (b) enzymatic modifications with beta-galactosidase (EC 3.2.1.23) or phosphatidylinositol-specific phospholipase C (EC 3.1.4.3). Using the first approach the majority of the glycosyl-phosphatidylinositol is found in the outer surface of intact hepatocytes, adipocytes, fibroblasts and lymphocytes, but not in erythrocytes which presented only a 20% of the total labelled glycosyl-phosphatidylinositol to the exterior. Upon insulin addition (10 nM), about 60% of the total glycosyl-phosphatidylinositol was hydrolysed in both hepatocytes and adipocytes but not in erythrocytes. In agreement with the extracellular localization in hepatocytes and with the proposed role of this glycolipid in insulin action, treatment of rat hepatocytes with beta-galactosidase from Escherichia coli, an enzyme that hydrolyses the oligosaccharide moiety of the glycosyl-phosphatidylinositol, cleaved 65% of the total glycophospholipid and blocked the effect of insulin (but not of glucagon) on pyruvate kinase (EC 2.7.1.40). Similar treatment with phosphatidylinositol-specific phospholipase C from Bacillus cereus hydrolysed 62% of the total glycosyl-phosphatidylinositol. From the various approaches used it is concluded that the majority of this glycophospholipid is at the outer surface in a variety of insulin-sensitive cells.
 ...
PMID:Asymmetric distribution of the phosphatidylinositol-linked phospho-oligosaccharide that mimics insulin action in the plasma membrane. 213 37

To ascertain whether mannose 6-phosphate-containing peptides that bind to the insulin-like growth factor II (IGF II)/mannose 6-phosphate receptor activate phospholipase C, we determined the effect of proliferin, transforming growth factor-beta 1 (TGF-beta 1) precursor, and beta-galactosidase on production of inositol trisphosphate (Ins-P3) in basolateral membranes isolated from the renal proximal tubule of dogs. Both proliferin and TGF-beta 1 precursor stimulated Ins-P3 production in a concentration-dependent manner. Maximal production was stimulated by approximately 10(-13) M of each peptide. beta-Galactosidase had no effect on Ins-P3 generation. Neither proliferin nor TGF-beta 1 precursor potentiated IGF II-stimulated Ins-P3 production. Mannose 6-phosphate itself had no effect on Ins-P3 generation. However, mannose 6-phosphate potentiated production stimulated by 10(-11) M proliferin or 10(-11) M TGF-beta 1 precursor while inhibiting production stimulated by 10(-14) M of either peptide. Addition of anti-mannose 6-phosphate receptor antibodies to basolateral membranes abolished proliferin and TGF-beta 1 precursor-stimulated Ins-P3 generation. We conclude that, in addition to IGF II, mannose 6-phosphate-containing ligands for the IGF II/mannose 6-phosphate receptor activate basolateral membrane phospholipase C. Such activation could reflect a common mechanism for signal transduction by these peptides mediated via the IGF II/mannose 6-phosphate receptor.
 ...
PMID:Mannose 6-phosphate-containing peptides activate phospholipase C in proximal tubular basolateral membranes from canine kidney. 216 41

Analysis of RNA isolated from Pseudomonas aeruginosa PA103 and PAKS grown under Fe2+-limiting (0.08 microgram/ml) and Fe2+-sufficient (10 micrograms/ml) conditions demonstrated that exotoxin A (ETA) expression is regulated by Fe2+ at the level of transcription. S1 nuclease mapping revealed two 5' termini of the tox transcript, 89 base pairs (bp) (S1A) and 62 bp (S1B) 5' to the ETA initiation codon. There appeared to be no consensus promoter sequence for either tox transcript. An 8-bp direct repeat was found 5' to the start of transcript S1A. Transcript S1B mapped 8 bp upstream of a dodecamer sequence conserved between the ETA and phospholipase C genes of P. aeruginosa. Multicopy plasmids in which the expression of ETA is directed from the Escherichia coli trp promoter (ptrpETA-RSF1010) or the tox promoter (pCMtox) were constructed and mobilized into a Tox-P. aeruginosa strain, WR5. WR5 synthesized and secreted high levels of ETA when it was expressed from the E. coli trp promoter; however, the synthesis of ETA from its own promoter in this strain was very low. These and other data suggest that the expression of ETA is under a positive control mechanism. A fusion of the ETA promoter fragment to lacZ was constructed. Use of this fusion plasmid revealed that this DNA fragment directed the synthesis of beta-galactosidase in E. coli at very low levels and that the synthesis of beta-galactosidase from this fusion in E. coli was not regulated by Fe2+.
 ...
PMID:Analysis of transcription of the exotoxin A gene of Pseudomonas aeruginosa. 243 Sep 45

Daily s.c. injection of gentamicin at either 100 mg/kg for 4 days or 60 mg/kg for 2 weeks produced nephrotoxicity in the adult rat as judged by an increase in urinary excretion of beta-galactosidase, beta-glucuronidase and beta-N-acetylglucosaminidase. The observed enzymuria was associated with significant elevation in total renal phospholipid, phosphatidylinositol, phosphatidylcholine and phosphatidylserine. In addition, gentamicin decreased the activities of renal cortical Na+-K+-adenosine triphosphatase, alkaline phosphatase as well as phospholipase C. Pyridoxal-5'-phosphate (250 mg/kg/day) administered i.p. for 4 or 14 days did not markedly alter the metabolic markers of kidney function. In rats simultaneously given pyridoxal-5'-phosphate and gentamicin for 4 days the vitamin failed to prevent either the antibiotic-induced decrease in renal phospholipase C and alkaline phosphatase or the increase in total renal phospholipid, phosphatidylinositol, phosphatidylcholine and phosphatidylserine. However, simultaneous pyridoxal-5'-phosphate and aminoglycoside treatment for 2 weeks proved effective in blockade of the gentamicin-induced kidney phospholipidosis, elevation in urinary beta-galactosidase, beta-glucuronidase and beta-N-acetylglucosaminidase, as well as reduction in renal phospholipase C and alkaline phosphatase. The gentamicin-induced nephrotoxicity was associated with a decrease in renal pyridoxal-5'-phosphate levels. In the simultaneous 4-day-treated rat the renal concentration of pyridoxal-5'-phosphate returned to approximate control values, whereas after 2 weeks the level of vitamin B6 was approximately 2-fold higher than control. Although pyridoxal-5'-phosphate in the simultaneous group lowered kidney gentamicin content by 40% after 4 or 14 days, protection from aminoglycoside-induced nephrotoxicity was apparent only after 2 weeks in our study.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Inhibition of gentamicin-induced nephrotoxicity by pyridoxal-5'-phosphate in the rat. 249 42

Prompt and early microbiological differential diagnosis is essential for clinical presumptive diagnosis of gas gangrene. The differential diagnosis includes clostridial myositis (gas gangrene), clostridial cellulitis and other gas producing infections. Examination of Gram preparation (bacterioscopy) and detection of the etiologic agent in muscle specimens are necessary for diagnosis. Clostridium perfringens has been shown as the causative organism of gas gangrene. A method is reported which allows the screening and identification of Clostridium perfringens from clinical specimens in a few hours. Using a medium yielding optimal growth and toxin production, pure cultures are centrifuged and subjected to rapid tests (detection of beta-galactosidase, phospholipase C).
 ...
PMID:[Rapid diagnosis in Clostridium perfringens wound infections]. 255 53

Polyclonal rabbit antiserum to the Triton X-114 phase material of Leishmania major, which comprises the surface and internal integral membrane proteins of the parasite, was used to screen a lambda gt11 genomic expression library. A recombinant clone producing a Mr 123,000 beta-galactosidase fusion protein was isolated. Antibodies affinity-purified on this fusion protein recognized a complex of three surface-oriented proteins of promastigotes of L. major of Mr 94,000, 90,000, and 80,000 that we have termed the promastigote surface Ag 2 (PSA-2) complex. The DNA sequence of the insert in this clone predicted the 3' end of an open reading frame encoding a hydrophobic C-terminus. The inferred C-terminal sequence was suggestive of a glycosylphosphatidyl-inositol membrane anchoring mechanism. Phosphatidylinositol-specific phospholipase C treatment of the native PSA-2 proteins caused a shift in their electrophoretic mobility with an apparent reduction in the molecular weight of the PSA-2 complex. After phospholipase C treatment these proteins also displayed the cryptic cross-reacting determinant recognized by antibodies to the Trypanosoma brucei variant surface Ag. Moreover, PSA-2, which previously partitioned in the detergent phase after Triton X-114 phase separation, became water-soluble after phospholipase C treatment. Immunoprecipitation of the PSA-2 proteins with sera directed to lectin-binding proteins indicated that these polypeptides may be differentially glycosylated. Finally, these PSA-2 proteins were recognized by sera from some patients with cutaneous leishmaniasis.
 ...
PMID:The PSA-2 glycoprotein complex of Leishmania major is a glycosylphosphatidylinositol-linked promastigote surface antigen. 259 73

Research has been carried out in order to clarify the chemical nature of cell receptors interacting with a fast growing strain of hepatitis A virus (HAV) producing a cytopathic effect on Frp/3 cells. Cell surface susceptibility to HAV attachment has been studied after treatment with enzymes acting on different chemical groupings. Results obtained showed a lowering of cell susceptibility to HAV infection following the action of phospholipase A2, phospholipase C, trypsin and beta-galactosidase. These data suggested that phospholipids, proteins and galactose participate to the cellular receptorial area for HAV.
 ...
PMID:Study of the chemical nature of Frp/3 cell recognition units for hepatitis A virus. 302 55

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.
 ...
PMID:Further evidence for lack of specific receptors for PGE2 in the rat ovary. 614 70


1 2 Next >>