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)

Subviral cores have been prepared from the oncornavirus-like particle found in human milks with the use of phospholipase C and ether or Sterox SL. The major protein of these cores has a molecular weight of 27,000 daltons, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein is found in the core fractions of reverse transcriptase-positive milks and is absent in negative milks. It is distributed in sucrose gradients only in those fractions containing cores and reverse transcriptase activity. The major core protein of the human milk oncornavirus-like particle is electrophoretically identical to the major core protein of the mouse mammary tumor virus.
...
PMID:Identification and isolation of the major core protein from the oncornavirus-like particle in human milk. 6 99

The role of phospholipids in the activity of UDP-D-galactose: D-xylose galactosyltransferase (galactosyltransferase I) from embryonic chick cartilage was investigated. Phospholipase C treatment of particulate galactosyltransferase I caused inactivation of this enzyme to the extent of 60 to 70% as well as hydrolysis of 75 to 80% of the membrane phospholipids. Addition of phospholipid restored activity to nearly control levels. The order of effectiveness of various phopholipids in reactivating phospholipase C-treated galactosyltransferase I was as follows: lysophosphatidylcholine, lysophosphatidylethanolamine, phosphatidylethanolamine, phosphatidylcholine. The effect of phospholipase A on galactosyltransferase I activity was also examined and was found to be concentration-dependent. At concentrations less than 10 mug/mg of pellet protein, phospholipase A slightly activated galactosyltransferase I. whereas at higher concentrations it inhibited the activity in a manner similar to phospholipase C. Galactosyltransferase I was activated moderately and also solubilized by treatment with Nonidet P-40 in the presence of 0.5 M KCl. Following solubilization and purification by gel filtration and affinity chromatography, galactosyltransferase I could be inactivated by detergent removal by dialysis and subsequently reactivated by addition of detergent. Neither phospholipase C treatment nor exogenous phospholipid had any significant effect on three of the other chondroitin sulfate glycosyltransferases (UDP-D-xylose: core protein xylosyltransferase, UDP-D-glucuronic acid:3-O-beta-D-galactosyl-D-galactose glucuronosyltransferase, and UDP-N-acetyl-D-galactosamine:(BlcUA-GalNAc-4-sulfate)j N-acetylgalactosaminyltransferase). On lipid analysis by thin layer chromatography, phosphatidylcholine and phosphatidylethanolamine were found to be the major phospholipids of particulate and solubilized glycosyltransferase preparations from embryonic chick cartilage, while lysopholipids of particulate and solubilized glycosyltransferase preparations from embryonic chick cartilage, while lysophosphatidylcholine and lysophosphatidylethanolamine were barely detectable components. The concentration of these specific phospholipids was diminished greatly following phospholipase C treatment.
...
PMID:Biosynthesis of chondroitin sulfate. Role of phospholipids in the activity of UDP-D-galactose: D-xylose galactosyltransferase. 94 16

Treating the liposome-intercalatable heparan sulfate proteoglycans from human lung fibroblasts and mammary epithelial cells with heparitinase and chondroitinase ABC revealed different core protein patterns in the two cell types. Lung fibroblasts expressed heparan sulfate proteoglycans with core proteins of approximately 35, 48/90 (fibroglycan), 64 (glypican), and 125 kDa and traces of a hybrid proteoglycan which carried both heparan sulfate and chondroitin sulfate chains. The mammary epithelial cells, in contrast, expressed large amounts of a hybrid proteoglycan and heparan sulfate proteoglycans with core proteins of approximately 35 and 64 kDa, but the fibroglycan and 125-kDa cores were not detectable in these cells. Phosphatidylinositol-specific phospholipase C and monoclonal antibody (mAb) S1 identified the 64-kDa core proteins as glypican, whereas mAb 2E9, which also reacted with proteoglycan from mouse mammary epithelial cells, tentatively identified the hybrid proteoglycans as syndecan. The expression of syndecan in lung fibroblasts was confirmed by amplifying syndecan cDNA sequences from fibroblastic mRNA extracts and demonstrating the cross-reactivity of the encoded recombinant core protein with mAb 2E9. Northern blots failed to detect a message for fibroglycan in the mammary epithelial cells and in several other epithelial cell lines tested, while confirming the expression of both glypican and syndecan in these cells. Confluent fibroblasts expressed higher levels of syndecan mRNA than exponentially growing fibroblasts, but these levels remained lower than observed in epithelial cells. These data formally identify one of the cell surface proteoglycans of human lung fibroblasts as syndecan and indicate that the expression of the cell surface proteoglycans varies in different cell types and under different culture conditions.
...
PMID:Differential expression of cell surface heparan sulfate proteoglycans in human mammary epithelial cells and lung fibroblasts. 133 31

B cell activation after Ag binding to membrane Ig (mIg) is mediated by a complex series of events that involves proximal activation of a tyrosine kinase and phospholipase C. Until recently it was unclear how mIgM and mIgD, with their limited cytoplasmic domains (three amino acids on each H chain), were able to couple to these secondary signal transducers. Studies of murine B cells conducted in several laboratories, including our own, suggest that products of the mb-1 (IgM-alpha or IgD-alpha) and B29 (Ig-beta, Ig-gamma) genes occur as disulfide-linked alpha/beta and alpha/gamma heterodimers that are noncovalently associated with mIgM and mIgD. Although studies utilizing Daudi and Raji cell lines indicate that human mIgM is also associated with a dimer containing the mb-1 gene product, the other molecules associated with the human receptor have not been identified. In this report we characterize the phosphoproteins that are noncovalently associated with mIgM on human tonsillar B cells and human pre-B cell lines. mIgM is noncovalently associated with a disulfide-linked heterodimer composed of variably glycosylated forms of two core proteins with apparent molecular mass of 26.5 and 27 kDa. Western blotting analysis reveals that the lower m.w. component of each of the mIgM-associated heterodimers and its 27-kDa deglycosylated core protein are reactive with antibodies against the murine B29 gene product. Thus, a product of the B29 gene is a component of the AgR complex in human and murine B cells, occurring as a disulfide linked dimer with product(s) of the mb-1 gene. Interestingly, mb-1 and B29 gene products expressed on human cells are much more heterogenously N-glycosylated than their murine B cell counterparts.
...
PMID:Human pre-B and B cell membrane mu-chains are noncovalently associated with a disulfide-linked complex containing a product of the B29 gene. 140 17

Rat ovarian granulosa cells synthesize two distinct species of plasma membrane-intercalated heparan sulfate (HS) proteoglycans; glycosylphosphatidylinositol (GPI)-anchored and core protein-intercalated HS proteoglycans. Both species of HS proteoglycans are primarily localized on the plasma membrane. Cell surface localization of GPI-anchored and protein-intercalated HS proteoglycans can be determined by their accessibility to exogenously added phosphatidylinositol-specific phospholipase C (PI-PLC) and trypsin, respectively. Kinetic parameters for the processes involving their transfer from the Golgi to the cell surface, endocytosis and secretion, and the modes of intracellular degradation were determined by metabolic labeling experiments using [35S]sulfate and various chase protocols in combination with the use of PI-PLC and trypsin in rat ovarian granulosa cells. The experiments demonstrated that (i) both HS proteoglycan species are transferred from the Golgi to the cell surface with an average transit time of approximately 12 min. (ii) GPI-anchored HS proteoglycans are endocytosed with a t1/2 approximately 3 h, without being shed into the medium, and they are rapidly degraded, t1/2 approximately 25 min, without generating recognizable degradation intermediates. (iii) Protein-intercalated HS proteoglycans are partly (approximately 30%) shed from the cell surface into the medium and the remaining approximately 70% are endocytosed with a t1/2 approximately 4 h. After endocytosis, they undergo a slow (t1/2 approximately 4 h) stepwise degradation generating distinct HS oligosaccharides as degradation intermediates. These results indicate that the GPI-anchored and the protein-intercalated HS proteoglycans have distinct secretory, endocytotic, and intracellular degradation pathways probably due to the differences in their anchor structures.
...
PMID:Glycosylphosphatidylinositol-anchored and core protein-intercalated heparan sulfate proteoglycans in rat ovarian granulosa cells have distinct secretory, endocytotic, and intracellular degradative pathways. 153 36

Cell surface heparan sulfate proteoglycan (HSPG) from metastatic mouse melanoma cells initiates cell adhesion to the synthetic peptide FN-C/H II, a heparin-binding peptide from the 33-kD A chain-derived fragment of fibronectin. Mouse melanoma cell adhesion to FN-C/H II was sensitive to soluble heparin and pretreatment of mouse melanoma cells with heparitinase. In contrast, cell adhesion to the fibronectin synthetic peptide CS1 is mediated through an alpha 4 beta 1 integrin and was resistant to heparin or heparitinase treatment. Mouse melanoma cell HSPG was metabolically labeled with [35S]sulfate and extracted with detergent. After HPLC-DEAE purification, 35S-HSPG eluted from a dissociative CL-4B column with a Kav approximately 0.45, while 35S-heparan sulfate (HS) chains eluted with a Kav approximately 0.62. The HSPG contained a major 63-kD core protein after heparitinase digestion. Polyclonal antibodies generated against HSPG purified from mouse melanoma cells grown in vivo also identified a 63-kD core protein. This HSPG is an integral plasma membrane component by virtue of its binding to Octyl Sepharose affinity columns and that anti-HSPG antibody staining exhibited a cell surface localization. The HSPG is anchored to the cell surface through phosphatidylinositol (PI) linkages, as evidenced in part by the ability of PI-specific phospholipase C to eliminate binding of the detergent-extracted HSPG to Octyl Sepharose. Furthermore, the mouse melanoma HSPG core protein could be metabolically labeled with 3H-ethanolamine. The involvement of mouse melanoma cell surface HSPG in cell adhesion to fibronectin was also demonstrated by the ability of anti-HSPG antibodies and anti-HSPG IgG Fab monomers to inhibit mouse melanoma cell adhesion to FN-C/H II. 35S-HSPG and 35S-HS bind to FN-C/H II affinity columns and require 0.25 M NaCl for elution. However, heparitinase-treated 125I-labeled HSPG failed to bind FN-C/H II, suggesting that HS, and not HSPG core protein, binds FN-C/H II. These data support the hypothesis that a phosphatidylinositol-anchored HSPG on mouse melanoma cells (MPIHP-63) initiates recognition to FN-C/H II, and implicate PI-associated signal transduction pathways in mediating melanoma cell adhesion to this defined ligand.
...
PMID:Cell surface phosphatidylinositol-anchored heparan sulfate proteoglycan initiates mouse melanoma cell adhesion to a fibronectin-derived, heparin-binding synthetic peptide. 160 92

The heparan sulphate (HS) proteoglycans associated with the cell layer of a rat osteosarcoma cell line [UMR 106-01 (BSP)] were compared with similar cell-associated proteoglycans from other cells, and their interaction with the plasma membrane was studied. HS proteoglycans were metabolically labelled by incubation of cell cultures with [3H]glucosamine or [3H]leucine and [35S]sulphate. HS proteoglycan core protein preparation generated by heparitinase digestion of the major species from UMR 106-01 (BSP) cells co-migrated on PAGE with identical preparations from ovarian granulosa cells and parathyroid cells (at approximately 70 kDa). The hydrophobic nature of the major HS proteoglycans from these diverse cell lines, based on elution position from octyl-Sepharose, were also comparable. Linkages of the HS proteoglycan to the cell membrane were investigated by labelling plasma-membrane preparations with a lipid soluble photoactivatable reagent, 3-(trifluoromethyl)-3- (m-[125I]iodophenyl)diazirine (TID), which selectively labels plasma-membrane-spanning peptide domains. Purified HS proteoglycan from UMR 106-01 (BSP) cells was shown to be accessible to the [125I]TID, and the core protein portion of the molecule was labelled, confirming its close association with the plasma membrane. Approx. 36% of 35S-labelled HS proteoglycans were released from the cell surface by phospholipase C (Bacillus thuringiensis), which specifically cleaves phosphatidylinositol-linked proteins. In the presence of insulin, the metabolism of the phospholipase C-sensitive population was unaltered; however, release of the phospholipase C-insensitive population into the medium was increased. These data indicate that a subpopulation of HS proteoglycans are covalently bound to the plasma membrane by a glycosylphosphatidylinositol structure, with the remainder representing those species directly inserted into the plasma membrane via a hydrophobic peptide domain. These observations are similar to those reported for ovarian granulosa cells [Yanagishita & McQuillan (1989) J. Biol. Chem. 264 17551-17558], and thus may represent a general phenomenon for many cell types.
...
PMID:Plasma-membrane-intercalated heparan sulphate proteoglycans in an osteogenic cell line (UMR 106-01 BSP). 163 8

Here we present evidence that a fibroblast heparan sulphate proteoglycan of approx. 300 kDa and with a core protein of apparent molecular mass 70 kDa is covalently linked to the plasma membrane via a linkage structure involving phosphatidylinositol. Phosphatidylinositol-specific phospholipase C releases such a heparan sulphate proteoglycan only from cells labelled with [35S]sulphate in the absence of serum. Cell cultures labelled with [3H]myo-inositol in the absence or presence of serum produce a radiolabelled heparan sulphate proteoglycan which was purified by gel-permeation chromatography and ion-exchange chromatography on MonoQ. Digestion with heparan sulphate lyase and analysis by gel-permeation chromatography and sodium dodecylsulphate-polyacrylamide gel-electrophoresis revealed that the 3H-label is associated with a core protein of apparent mass 70 kDa.
...
PMID:A fibroblast heparan sulphate proteoglycan with a 70 kDa core protein is linked to membrane phosphatidylinositol. 213 53

Two mAbs raised against the 64-kD core protein of a membrane heparan sulfate proteoglycan from human lung fibroblasts also recognize a nonhydrophobic proteoglycan which accumulates in the culture medium of the cells. Pulse-chase studies suggest that the hydrophobic cell-associated forms act as precursors for the nonhydrophobic medium-released species. The core proteins of the medium-released proteoglycans are slightly smaller than those of the hydrophobic cell-associated species, but the NH2-terminal amino acid sequences of both forms are identical. The characterization of human lung fibroblast cDNAs that encode the message for these core proteins and the effect of bacterial phosphatidylinositol-specific phospholipase C suggest that the hydrophobic proteoglycan is membrane-anchored through a phospholipid tail. These data identify a novel membrane proteoglycan in human lung fibroblasts and imply that the shedding of this proteoglycan may be related to the presence of the phospholipid anchor.
...
PMID:Molecular cloning of a phosphatidylinositol-anchored membrane heparan sulfate proteoglycan from human lung fibroblasts. 214 68

Schwann cells synthesize both hydrophobic and peripheral cell surface heparan sulfate proteoglycans (HSPGs). Previous analysis of the kinetics of radiolabeling suggested the peripheral HSPGs are derived from the membrane-anchored forms (Carey, D., and D. Evans. 1989. J. Cell Biol. 108:1891-1897). Peripheral cell surface HSPGs were purified from phytic acid extracts of cultured neonatal rat sciatic nerve Schwann cells by anion exchange, gel filtration, and laminin-affinity chromatography. Approximately 250 micrograms of HSPG protein was obtained from 2 X 10(9) cells with an estimated recovery of 23% and an overall purification of approximately 2000-fold. SDS-PAGE analysis indicated the absence of non-HSPG proteins in the purified material. Analysis of heparinase digestion products revealed the presence of at least six core protein species ranging in molecular weight from 57,000 to 185,000. The purified HSPGs were used to produce polyclonal antisera in rabbits. The antisera immunoprecipitated a subpopulation of 35SO4-labeled HSPGs that were released from Schwann cells by incubation in medium containing phosphatidylinositol-specific phospholipase C (PI-PLC); smaller amounts of immunoprecipated HSPGs were also present in phytic acid extracts. In the presence of excess unlabeled PI-PLC-released proteins, immunoprecipitation of phytic acid-solubilized HSPGs was inhibited. SDS-PAGE analysis of proteins immunoprecipitated from extracts of [35S]methionine labeled Schwann cells demonstrated that the antisera precipitated an HSPG species that was present in the pool of proteins released by PI-PLC, with smaller amounts present in phytic acid extracts. Nitrous acid degradation of the immunoprecipitated proteins produced a single 67,000-Mr core protein. When used for indirect immunofluorescence labeling, the antisera stained the external surface of cultured Schwann cells. Preincubation of the cultures in medium containing PI-PLC but not phytic acid significantly reduced the cell surface staining. The antisera stained the outer ring of Schwann cell membrane in sections of adult rat sciatic nerve but did not stain myelin or axonal membranes. This localization suggests the HSPG may play a role in binding the Schwann cell plasma membrane to the adjacent basement membrane surrounding the individual axon-Schwann cell units.
...
PMID:Identification of a lipid-anchored heparan sulfate proteoglycan in Schwann cells. 217 60


1 2 3 Next >>

---