Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.21 (beta-glucosidase)
 3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A radioisotopic assay was developed to quantitate the binding of Leishmania donovani promastigotes to hamster peritoneal macrophages in vitro. The binding was temperature dependent and required no serum factors. Binding was reduced by preloading macrophages with zymosan granules or unlabeled promastigotes, but not with latex leads or opsonized erythrocytes. Binding was reduced by 10 mM EGTA that was reversible by the addition at an equimolar concentration of calcium, but not magnesium ions. Sialic acid, D-glucose, D-mannose and their derivatives reduced the binding, whereas L-fucose, D-galactose and their related sugars did not. Pretreatment of promastigotes with neuraminidase, alpha-mannosidase, alpha-N-acetylglucosaminidase or beta-glucosidase reduced their binding to macrophages. Prior trypsinization of either macrophages or promastigotes also substantially reduced the binding. At 4 degrees C, prior opsonization of promastigotes with subagglutination titers of antiserum doubled the level of binding but in combination with Protein A reduced it to 50% of its normal binding level. Prior opsonization of macrophages decreased their binding to promastigotes significantly at 4 or 37 degrees C. The results indicate that binding of Leishmania donovani promastigotes to hamster peritoneal macrophages is a ligand-receptor interaction involving their antigenic surface membrane proteins. The binding ligands of the parasites appear to have at least sialol, glucosyl, mannosyl and N-acetylglucosaminyl terminal residues as binding determinants. Thus, receptor-mediated endocytosis, defined in a broader sense, appears to be the mechanism by which leishmanias gain entry into macrophages.
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PMID:Leishmania donovani-macrophage binding mediated by surface glycoproteins/antigens: characterization in vitro by a radioisotopic assay. 732 88

Structures of the N-linked oligosaccharide attached to the heavy chain of a heterologous murine IgG2a produced from Trichoplusia ni (TN-5B1-4, High Five) insect cells were characterized. Coexpression of the chaperone immunoglobulin heavy chain-binding protein (BiP) in the baculovirus-infected insect cells increased the soluble intracellular and secreted IgG level. This facilitated the detailed analysis of N-glycans from both intracellular and secreted IgG. Following purification of the immunoglobulins using Protein A-Sepharose, glycopeptides, prepared by trypsin-chymotrypsin digestion, were further digested with glycoamidase from sweet almond emulsin to obtain the oligosaccharide moieties. The resulting oligosaccharides were then reductively aminated with 2-aminopyridine and the structures identified by two-dimensional high performance liquid chromatography mapping (Tomiya, N., Awaya, J., Kurono, M., Endo, S., Arata, Y., and Takahashi, N. (1988) Anal. Biochem. 171, 73-90). The N-glycans obtained from the secreted IgG contain 35% complex type, some with terminal galactose residues at either alpha1, 3-Man or alpha1,6-Man branches of the Man3GlcNAc2 core. The remaining oligosaccharides detected in the secreted IgG were principally hybrid (30%) and paucimannosidic (35%) type N-glycans. Most (84%) of these secreted glycoforms contained fucose alpha1, 6-linked to the innermost GlcNAc residue and the presence of a potentially allergenic fucose alpha1,3-linked to the innermost GlcNAc residue was also detected. In contrast, the intracellular immunoglobulins included 50% high mannose-type N-glycans with lower levels of complex, hybrid, and paucimannosidic-type structures. Reverse phase one-dimensional high performance liquid chromatography analysis of the IgG N-glycans in the absence of heterologous BiP exhibited a similar distribution of intracellular and secreted glycoforms. These studies indicate that Trichoplusia ni TN-5B1-4 cells are capable of terminal galactosylation. However, the processing pathways in these cell lines appear to diverge from mammalian cells in the formation of paucimannosidic structures, in the presence of alpha1,3-fucose linkages, and in the absence of sialylation.
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PMID:Differential N-glycan patterns of secreted and intracellular IgG produced in Trichoplusia ni cells. 908 32