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 surface expression of prion protein (PrP(C)) on human platelets, as detected by flow cytometry with the monoclonal antibody 3F4, increased more than two-fold (4300 v 1800 molecules/platelet) after full activation. Maximal surface expression of PrP(C) occurred within 3 min of platelet activation and declined to approximately half of maximal levels by 2 h at 37 degrees C. In comparison, PrP(C) on the surface of platelets, activated at 22 degrees C took 10 min to reach maximum but then remained constant for 2 h. In sonicated resting platelets, PrP(C) and P-selectin remained in intact granules after subcellular fractionation. Both glycoproteins were found in the ruptured membranes of activated platelets, suggesting that the PrP(C) was translocated from internal granules to the plasma membrane during activation, as is P-selectin. Platelet PrP(C) was not removed from the surface of platelets by phosphatidylinositol-specific phospholipase C (PIPLC) treatment but was degraded by proteinase K. Platelets may serve as a useful model for following the cellular processing of PrP(C).
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PMID:Increased expression of phosphatidylinositol-specific phospholipase C resistant prion proteins on the surface of activated platelets. 1099 93

An attempt was made to determine the receptor for the hemolysin of Fusobacterium necrophorum using horse erythrocyte or its membranes as target. The spectrum of erythrocyte sensitivity has indicated that horse, dog and mouse erythrocytes are highly sensitive whereas cattle, sheep, goat and chicken red blood cells are insensitive to this hemolysin. A high correlation between sensitivity and phosphatidylcholine content of the erythrocyte membranes was noted. Binding of hemolysin to horse erythrocyte membranes was reduced significantly by prior treatment of membranes with phospholipase A2 but not with phospholipase C. Pretreatment of erythrocyte membranes with pronase, proteinase K, trypsin or neuraminidase did not alter binding of hemolysin to the membranes, suggesting that protein or sialyl residues are not involved as receptors. Gas liquid chromatography analysis showed that the fatty acid profile from hydrolysis of bovine liver phosphatidylcholine by hemolysin and phospholipase A2 were similar. In conclusion, this report presents evidence that phosphatidylcholine may be acting as a possible receptor for the hemolysin of F. necrophorum.
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PMID:The erythrocyte receptor for Fusobacterium necrophorum hemolysin: phosphatidylcholine as a possible candidate. 981 64

This work presents evidence on the association of active DDC molecules with membranes in mammalian brain. L-DOPA decarboxylase (DDC) is generally considered to be a cytosolic enzyme. Membrane-associated DDC was detected by immunoblotting and enzymatic assay experiments. DDC activity and immunoreactivity could be partially extracted from mammalian brain membranes by detergent. Fractionation of membranes by temperature-induced phase separation in Triton X-114, resulted in the recovery of membrane-associated DDC in separation phases where integral and hydrophobic membrane proteins separate. Treatment of membranes with phosphatidylinositol-specific phospholipase C or proteinase K, did not elute membrane-associated DDC activity, suggesting that a population of DDC molecules exist embedded within membranes. The elucidation of the functional significance of the enzyme's association with membranes could provide us with new information leading to the better understanding of the biological pathways that DDC is involved in.
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PMID:L-DOPA decarboxylase association with membranes in mouse brain. 1151 73

Wound healing is a complex process that involves cell communication, migration, proliferation, and changes in gene expression. One of the first events after injury is the rapid release of Ca(2+) that propagates as a wave to neighboring cells (Klepeis et al. [2001]: J. Cell. Sci. 114:4185-4195). Our goal was to examine the signaling events induced by cellular injury and identify extracellular molecules that induce the activation of extracellular signal responsive kinase (ERK) (p42/44). In this study we demonstrated that injury induced ERK1/2 activation occurred within 2 min and was negligible by 15 min. Treatment of unwounded cells with wound media caused activation of ERK that could be inhibited by apyrase III. Stimulation with epidermal growth factor (EGF) did not mimic the injury response and it was not detected in the wound media. To identify the active component, size fractionation was performed and factor(s) less than 3 kDa that induced the release of Ca(2+) and activation of ERK1/2 were identified. Activity was not altered by heat denaturation, incubation with proteinase K but it was lost by treatment with apyrase. Adenosine triphosphate (ATP), uridine triphosphate (UTP), adenosine diphosphate (ADP), and uridine diphosphate (UDP) promoted activation by 2 min with similar profiles as that generated by injury. Preincubation with phospholipase C inhibitor, U73122, inhibited activation that was induced by injury and/or nucleotides. Lack of activation by alpha-beta-methylATP (alpha, beta-MeATP) and beta-gamma-methylATP (beta, gamma-MeATP) to purinergic (P)2X receptors further indicated that activation occurs via P2Y and not P2X purinergic receptors. These results indicate that injury-induced activation of ERK1/2 is mediated by a P2Y signaling pathway.
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PMID:Cellular injury induces activation of MAPK via P2Y receptors. 1503 29

The activity of Clostridium septicum alpha-toxin was determined in erythrocytes of various animals, with sensitivities observed in the order of mouse, rat, canine, equine, rabbit, chicken, bovine, swine and ovine. Temperature and protease treatment affected the sensitivity of erythrocytes to alpha-toxin. Proteinase K treatment decreased the sensitivity of murine, canine, equine and bovine erythrocytes, but ovine erythrocytes did not change the sensitivity to alpha-toxin activity. On the other hand, the activity of alpha-toxin on swine erythrocytes increased after treatment with proteinase K, trypsin, chymotrypsin or lysyl endopeptidase. Toxin overlay assay showed that alpha-toxin bound to erythrocyte membrane proteins with a molecular mass of 30 to 45-kDa in mouse, equine, bovine, swine and chicken, whereas in rat erythrocyte membranes the toxin reacted with 100-kDa protein. The treatment of murine and swine erythrocyte membranes with phosphatidylinositol-specific phospholipase C resulted in liberation of the toxin-binding protein from the individual membranes in a native state. These results show that alpha-toxin associates with specific erythrocyte membrane proteins in any animal species, and are subsets of glycosylphosphatidylinositol-anchored proteins in various animal species. These results may reflect distinct characteristics of the hemolytic activity of alpha-toxin in response to various erythrocytes.
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PMID:Relationship between Clostridium septicum alpha-toxin activity and binding to erythrocyte membranes. 1569 97

Enterovirus 70 (EV70), the causative agent of acute hemorrhagic conjunctivitis, exhibits a restricted tropism for conjunctival and corneal cells in vivo but infects a wide spectrum of mammalian cells in culture. Previously, we demonstrated that human CD55 is a receptor for EV70 on HeLa cells but that EV70 also binds to sialic acid-containing receptors on a variety of other human cell lines. Virus recognition of sialic acid attached to underlying glycans by a particular glycosidic linkage may contribute to host range, tissue tropism, and pathogenesis. Therefore, we tested the possibility that EV70 binds to alpha2,3-linked sialic acid, like other viruses associated with ocular infections. Through the use of linkage-specific sialidases, sialyltransferases, and lectins, we show that EV70 recognizes alpha2,3-linked sialic acid on human corneal epithelial cells and on U-937 cells. Virus attachment to both cell lines is CD55 independent and sensitive to benzyl N-acetyl-alpha-D-galactosaminide, an inhibitor of O-linked glycosylation. Virus binding to corneal cells, but not U-937 cells, is inhibited by proteinase K, but not by phosphatidylinositol-specific phospholipase C treatment. These results are consistent with the idea that a major EV70 receptor on corneal epithelial cells is an O-glycosylated, non-glycosyl phosphatidylinositol-anchored membrane glycoprotein containing alpha2,3-linked sialic acid, while sialylated receptors on U-937 cells are not proteinaceous.
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PMID:Enterovirus 70 binds to different glycoconjugates containing alpha2,3-linked sialic acid on different cell lines. 1589 Sep 48

Bacterial recognition of host sialic acid-containing receptors plays an important role in microbial colonization of the human oral cavity. The aggregation of human platelets by Streptococcus gordonii DL1 is implicated in the pathogenesis of infective endocarditis. In addition, we consider that hemagglutination of this organism may act as an additive factor to increase the severity of this disease. We previously reported that this interaction requires the bacterial expression of a 203-kDa protein (Hsa), which has sialic acid-binding activity. In the present study, we confirmed that erythrocyte surface sialoglycoproteins are the receptors for Hsa. We examined the effects of proteinase K, chymotrypsin, phospholipase C, and alpha(2-3) or alpha(2-3, 6, 8) neuraminidase on hemagglutination activity and found that the interaction occurs between Hsa and alpha2-3-linked sialic acid-containing proteins of erythrocytes. We expressed recombinant NR2, which is the putative binding domain of Hsa, fused with GST in Escherichia coli BL21. Dot-blot analysis demonstrated that GST-HsaNR2 binds both glycophorin A (GPA) and band 3. Moreover, GPA and a small amount of band 3 were detected by GST pull-down assays. These findings indicate that S. gordonii Hsa specifically binds to GPA and band 3, alpha2-3-linked sialic acid membrane glycoproteins.
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PMID:Hsa, an adhesin of Streptococcus gordonii DL1, binds to alpha2-3-linked sialic acid on glycophorin A of the erythrocyte membrane. 1838 Aug 4

An endogenous inhibitor of L-Dopa decarboxylase activity was identified and purified from human placenta. The endogenous inhibitor of L-Dopa decarboxylase (Ddc) was localized in the membrane fraction of placental tissue. Treatment of membranes with phosphatidylinositol-specific phospholipase C or proteinase K did not affect membrane-associated Ddc inhibitory activity, suggesting that a population of the inhibitor is embedded within membranes. Purification was achieved by extraction from a nondenaturing polyacrylamide gel. The purification scheme resulted in the isolation of a single 35 kDa band, bearing L-Dopa decarboxylase inhibitory activity. The purified inhibitor was identified as Annexin V. The elucidation of the biological importance of the presence of an L-Dopa decarboxylase activity inhibitor in normal human tissues could provide us with new information leading to the better understanding of the biological pathways that Ddc is involved in.
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PMID:Detection, purification and identification of an endogenous inhibitor of L-Dopa decarboxylase activity from human placenta. 1900 53

Host immune responses conducted against antigens of Eimeria bovis are key factors for the development of protective immunity against this protozoan disease. In this study we investigated the expression of E. bovis-derived antigens on the host cell surface membrane during E. bovis first merogony in vitro. Host cells carrying E. bovis-meront I stages expressed E. bovis host cell surface antigens (EbHCSAg) on their surface membrane which were recognised by hyperimmune sera of calves and by sera from rats immunized with E. bovis merozoites I, when tested by indirect immune fluorescent antibody test (IIFAT), laser scanning confocal microscopy (LSCM) and immune electron microscopy. Expression of EbHCSAg on permissive host cells was earliest detected 7 days p. i., thus coinciding with the onset of the parasite replication. Membrane-associated EbHCSAg were removed from infected host cells by proteinase K, partially by Triton X-100, Triton X-114 and Triton X-405, but not by 1 M NaCl, CHAPS or phospholipase C treatment. Antibodies, affinity-purified on paraformaldehyde/glutardialdehyde (PAGA)-fixed E. bovis meront I-infected bovine host cells bound to the surface meront I-carrying cells and to merozoites I (IIFAT, LSCM) but, in contrast to untreated sera, not to sporozoites. When tested on methanol-fixed merozoites I and sporozoites by IIFAT, affinity-purified antibodies bound to structures in the apical complex area of merozoites I, but not to sporozoites, whilst untreated sera caused diffuse labelling of internal structures of both parasite stages. Immune electron microscopy demonstrated binding of affinity-purified antibodies to micronemes and dense granules of merozoites I. Although the function of EbHCSAg is still unknown, results of this study might suggest an involvement in the development of protective immunity against E. bovis infections.
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PMID:Eimeria bovis meront I-carrying host cells express parasite-specific antigens on their surface membrane. 2001 10

Staphylococcus aureus, a major opportunistic pathogen, is a leading cause of biofilm-related infections in clinical practice. Staphylococcal biofilms are highly resistant to antibacterial medicines and immune effector cells. The main result of our work is the discovery of nano-vesicles in the supernatant of the human neutrophil-S. aureus biofilm system. We also found that phospholipase C treatment causes complete destruction of these vesicles. While the addition of proteinase K led to a partial structural disorganization of the vesicles, DNase treatment did not influence the vesicle structure. These observations allowed us to conclude that phospholipids and proteins play a structure-forming role in the formation of these nano-vesicles. The vesicles demonstrated anti-biofilm activities when tested against Staphylococcus epidermidis (strains 178M and 328/5) biofilms, but were ineffective for S. aureus (strains 5983/2, 5663 and 18A) biofilms.
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PMID:Vesicle formation as a result of interaction between polymorphonuclear neutrophils and Staphylococcus aureus biofilm. 2369 65


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