Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The disruption of the molecular organization of the plasma membrane of leukocytes by phagocytosable particles, or by agents such as surfactants, antibodies, phospholipase C, fatty acids and chemotactic factors, leads to a stimulation of the phagocyte oxidative metabolism. Concanavalin A (Con A) has been used as a tool to study the mechanism of this metabolic regulation. The binding of Con A to the surface of polymorphonuclear leukocytes (PMNL) or macrophages produces a rapid enhancement of oxygen uptake and glucose oxidation through the hexose monophosphate pathway (HMP). This is explained by an activation of the granular NADPH oxidase, the key enzyme in the metabolic stimulation. The effect of Con A is not due to endocytosed lectin, since Con A covalently coupled to large sepharose beads still acts as stimulant. The metabolic changes caused by Con A are reversible. If, after the onset of stimulation, sugars with high affinity for Con A are added to the leukocyte suspension, the activity of granular NADPH oxidase and the rate of respiration and glucose oxidation return to their resting values. The metabolic burst, while partially supressed by treatment of PMNL with iodoacetate, sodium flouride and cytochalasin B, is slightly increased by colchicine. Con A induces a selective release of granular enzymes (beta-glucuronidase, peroxidase, alkaline phosphatase) from PMNL, whereas no leakage of cytoplasmic enzymes is observed. The enzyme release is inhibited by iodoacetate and by drugs known to increase cell levels of cyclic AMP. Based on a current view of the mode of interaction between Con A and cell surfaces, a model of the metabolic disruption of leukocytes is presented.
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PMID:Concanavalin A as a probe for studying the mechanism of metabolic stimulation of leukocytes. 16 45

Cationic local anesthetics have been reported to influence cellular responses to surface stimuli by interfering with the function of microtubules and microfilaments. Since unimpaired microtubule and microfilament functions are required by human polymorphonuclear leukocytes in order to respond normally to surface stimulation, we have studied effects of the local anesthetic, tetracaine on the function and morphology of these cells in vitro. Tetracaine (0.25--1.0 mM) significantly reduced extracellular release of the lysosomal enzymes, beta-glucuronidase and lysozyme from polymorphonuclear leukocytes exposed to serum-treated zymosan (a particulate stimulus), zymosan-treated serum (a soluble stimulus), and to the surface-active lectin, concanavalin A. Tetracaine also significantly reduced superoixde anion production (superoxide dismutase-inhibitable cytochrome c reduction) by these cells. Tetrancaine was not cytotoxic and its effects could be reversed completely by washing cells once with buffer. Electron microscope examination of tetracaine-treated cells revealed marked alterations of surface membranes. Microtubules and microfilaments appeared normal in "resting" polymorphonuclear leukocytes, but the increase in microtubules normally observed in stimulated cells was not seen after tetracaine treatment. These results suggest that tetracaine interferes with those interactions between immune reactants and the polymorphonuclear leukocyte cell surface which provoke exocytosis and increased oxidative metabolism.
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PMID:Influence of local anesthetics upon human polymorphonuclear leukocyte function in vitro. Reduction of lysosomal enzyme release and superoxide anion production. 19 3

The binding of 22 human liver hydrolase activities by immobilized lectins of six different carbohydrate specificities, namely alpha-D-mannose (glucose), D-N-acetylglucosamine, D-N-acetylgalactosamine, L-fucose, alpha-D-galactose and beta-D-galactose, were examined. Differences in binding among these enzymes and within specific enzymes were observed. For example, the neutral forms of alpha-mannosidase and beta-xylosidase were bound by the Ulex europaeus lectin I (specific for L-fucose), whereas the acidic forms were not. Bandierea simplicifolia lectin (specific for alpha-galactose) bound 65% of beta-glucuronidase activity; recycling experiments demonstrated complete binding of the enzyme that had been eluted with the competitor D-galactose and no binding of the fraction that was not initially bound. These results suggested the presence of two forms of this enzyme. Similar data were obtained for acidic beta-galactosidase activity. These experiments may provide the basis for the expanded use of immobilized lectins for purification and characterization of hydrolases and other glycoproteins.
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PMID:Binding of human liver hydrolases by immobilized lectins. 42 66

The purification of rat liver beta-glucuronidase from a lysosomal fraction by methods including affinity chromatography, chromatofocusing and preparative PAGE steps is described. Molecular weights of 300,000 and 150,000 were estimated by two dimensional gradient PAGE/immunoelectrophoresis of the lysosomal extract. Isoelectrofocusing in agarose gel followed by immunoelectrophoresis in the second dimension revealed the presence of at least five maxima in the range pH 4.3-7.4. The structural assessment of the carbohydrate chains of lysosomal and microsomal beta-glucuronidase was performed by lectin affinity immunoelectrophoresis. Reaction with Concanavalin A indicated the presence of bi-antennary complex, oligomannosidic and hybrid type structures, whereas the absence of tri- and tetra-antennary complex type structures was deduced from the lack of interaction with phytohemagglutinin-L. The reaction with Lens culinaris agglutinin, Pisum sativum agglutinin and Lotus tetragonolobus lectin revealed that part of the glycans contained a fucose alpha(1-6)-linked to the N-acetylglucosamine attached to asparagine. The presence of terminal beta(1-4)-galactose residues was detected with Ricinus communis agglutinin I.
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PMID:Purification of beta-glucuronidase and structural assessment of the carbohydrate chains by lectin affinity immunoelectrophoresis. 184 76

IgE binds to two types of Fc receptors, called Fc epsilon R1 (or high-affinity Fc epsilon R) and Fc epsilon R2 (or low-affinity Fc epsilon R). The Fc epsilon R1 is composed of four polypeptide chains, one alpha, one beta, and two gamma chains. The alpha chain contains the IgE binding site and is a member of the immunoglobulin supergene family. The Fc epsilon R2, also called CD23, consists of one polypeptide chain which shows homology to animal lectin receptors. Fc epsilon R1 are expressed on mast cells and basophils. Crosslinking of the Fc epsilon R1 induces immediate release of mediators of inflammation such as histamine and leukotrienes and delayed secretion of interleukins 4, 5, and 6. Fc epsilon R2 are expressed on resting mu delta + B cells, monocytes/macrophages (M phi), eosinophils, and platelets but rarely on T cells. Interleukin-4 upregulates Fc epsilon R2 expression on B cells and M phi. The functions of Fc epsilon R2 on the different cell types are not fully established and are controversial. Fc epsilon R2 on M phi, eosinophils, and platelets mediate cytotoxicity to schistosomules, enhance phagocytosis, and induce the release of granule enzymes. However, M phi from patients with atopic dermatitis expressing significantly more Fc epsilon R2 than M phi from normals do not release more leukotriene C4, prostaglandin E2, or beta-glucuronidase after incubation with aggregated IgE than normal monocytes. Furthermore, aggregated IgG1 is much more efficient than IgE in inducing mediator release from M phi and IgG1 antibodies are not known to induce immediate-type hypersensitivity reactions. Therefore, definitive proof that Fc epsilon R2 are involved in the pathogenesis of allergic disorders is still lacking. IL-4 appears to play a central role in immediate-type hypersensitivity. It induces human B cells to secrete IgE and IgG4, Ig isotypes typical for antibodies to helminthic parasites and allergens. IL-4 stimulates mast cell growth and upregulates Fc epsilon R2 expression. Interferon-gamma and IL-2 inhibit the IL-4-induced IgG4 and IgE secretion. Whether the abnormally high IgE antibody production in atopic patients is the result of overproduction of IL-4 or deficient IFN-gamma/IL-2 production is presently unknown.
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PMID:Fc receptors for IgE and interleukin-4 induced IgE and IgG4 secretion. 219 Oct 55

Endogenous ligands for the hepatic lectin which is specific for mannose and N-acetylglucosamine (mannan-binding protein, MBP) were isolated from rat liver rough microsomes and primary cultured hepatocytes by affinity chromatography on an immobilized MBP column. Western blotting using specific antisera revealed that serum glycoproteins, alpha 1-macroglobulin, alpha 1-antitrypsin, and alpha 1-acid glycoprotein, and a lysosomal enzyme, beta-glucuronidase were the major constituents of the endogenous ligands. These endogenous ligands consisted of high mannose-type oligosaccharides of Man9GlcNAc2 and Man8GlcNAc2, and had rapid turnover rates with an average half-life of 45 min, indicating that they were mainly composed of biosynthetic intermediates of glycoproteins. In view of the identification of the endogenous ligands as the biosynthetic intermediates of glycoproteins, the possible functions of the intracellular lectin are discussed in relation to the intracellular transport of glycoproteins.
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PMID:Isolation and characterization of endogenous ligands for liver mannan-binding protein. 245 42

Polymorphonuclear leukocyte (PMN)-dependent destruction of Actinomyces viscosus T14V is initiated by the recognition of galactose-containing receptors on sialidase-treated PMNs by the lectin associated with the type 2 fimbriae of these bacteria. A. viscosus T14V also stimulates the respiratory burst in PMNs as well as the release of contents of the secondary granules, as determined by the presence of lactoferrin in the culture supernatants. Under the experimental conditions employed, these bacteria do not induce the release of beta-glucuronidase, a constituent of primary granules. None of the three PMN responses studied occurs in cultures containing a mutant of A. viscosus T14V that lacks fimbriae. Activation of the PMNs is mediated by the lectin associated with the type 2 fimbriae, as demonstrated by the finding that beta-linked galactosides inhibit stimulation of the respiratory burst. Thus, the interaction of the Actinomyces fimbrial lectin with its complementary receptors on PMNs results not only in killing of these bacteria but also in the release of reactive oxygen intermediates and enzymes that may be detrimental to surrounding host tissues.
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PMID:Stimulation of superoxide and lactoferrin release from polymorphonuclear leukocytes by the type 2 fimbrial lectin of Actinomyces viscosus T14V. 289 19

Three fluorescein-labeled lectins were shown to bind differentially to cell surfaces in different epithelial layers of rat oral mucosa regardless of the age or the site of origin of the tissue. Griffonia simplicifolia (GS-1-B4), specific for alpha-D-galactosyl end groups, labeled basal cells only; Ulex europeus (Ulex 1) specific for alpha-L-fucosyl groups labeled spinous cells; and Bandeiraea simplicifolia (BSII), specific for N-acetyl-D-glucosamine, labeled cornified cells. Pretreatment of sections with alpha-galactosidase completely abolished the staining of basal cells by GS-1-B4, but had no effect on the staining of spinous cells by Ulex 1. In contrast, alpha-fucosidase abolished the staining of spinous cells by Ulex 1 and caused staining of both basal and spinous cells by GS-1-B4. Neuraminidase and chondroitinase ABC produced results similar to one another, with staining of basal cells by GS-1-B4 and labeling of both basal and spinous cells with Ulex 1. beta-galactosidase, beta-glucuronidase, and testicular hyaluronidase did not affect the staining pattern of GS-1-B4 or Ulex 1, whereas chymotrypsin completely abolished any staining with either lectin. The results demonstrate a complex arrangement of cell surface carbohydrates in the epithelium of rat oral mucosa. The findings indicate a possible simplification in the spatial arrangements of cell surface carbohydrates during the differentiation of basal to spinous cells.
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PMID:Preferential lectin binding to specific layers of rat oral epithelium and modification by enzyme pretreatment. 299 51

The accumulation of the relatively large amounts of beta-glucuronidase in microsomal fractions of normal mice depends on formation of complexes with the protein egasyn. Unexpectedly, it was found that the egasyn gene also affects the processing of beta-glucuronidase, which is segregated to lysosomes. In egasyn-positive mice lysosomal beta-glucuronidase from liver has a mean pI of 5.9 with a minor proportion at pI 5.4, whereas in egasyn-negative mice the proportion of the two lysosomal forms is reversed. Combined experiments measuring susceptibility to neuraminidase and to endoglycosidase H and specific binding to Ricinus communis lectin-agarose columns showed that the alterations in isoelectric point were associated with a decrease in complex oligosaccharides of lysosomal beta-glucuronidase in egasyn-positive mice. Since this alteration occurs not only in a congenic strain carrying the Eg0 gene but also in several other inbred strains that are homozygous for this gene, it is considered to be a genuine effect of the Eg gene rather than other genes that might regulate oligosaccharide processing. Also, the alteration is likely to be a result of direct physical interaction of the egasyn protein and lysosomal beta-glucuronidase, since a second lysosomal enzyme, beta-galactosidase, which does not form complexes with egasyn, is unaffected. The results suggest a model in which egasyn not only causes accumulation of beta-glucuronidase in the microsomal compartment but also acts upon the precursor to lysosomal beta-glucuronidase to alter its interaction with trans-Golgi-apparatus processing enzymes.
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PMID:The egasyn gene affects the processing of oligosaccharides of lysosomal beta-glucuronidase in liver. 310 73

The structure of the basement membrane of the high endothelium of reactive human lymph nodes was investigated by techniques selective for carbohydrates (periodic acid-Schiff; critical electrolyte concentration staining with Alcian Blue; lectin histochemistry), specific proteins (immunohistochemistry for laminin and fibronectin) and by conventional techniques of light and transmission electron microscopy. Adjacent small lymphocytes were assigned to B and T cell subsets by use of monoclonal antibodies and they were analysed for non-specific esterase, beta-glucuronidase, beta-N-acetylglucaminidase and proteolytic activities. The basement membranes were shown to be distinctive and to contain three layers, of differing laminin, glycosaminoglycan and glycoprotein oligosaccharide content. Certain lymphocytes (probably T) contained enzymes potentially able to degrade some components of these basement membranes.
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PMID:The structure of the basement membrane of human lymph node high endothelial venules: an ultrastructural, histochemical and immunocytochemical study. 353 3


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