Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P17931 (galectin-3)
 2,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Identification of the material present in human serum which is responsible for inhibition of binding of desialylated glycoproteins to rat hepatocyte membranes was accomplished by means of affinity chromatography using Sephadex to which the galactose-specific lectin, Ricinus Communis Agglutinin (RCAI) was covalently bound. RCAI-Sephadex was capable of extraction of virtually all of the inhibitory activity from cirrhotic serum. The RCA I-bound inhibitory activity could be eluted with 0.05 M D-galactose. The D-galactose eluate when subjected to radioimmunoelectrophoresis against a number of specific antibodies to human serum glycoproteins produced arcs corresponding to alpha 1-acid glycoprotein, alpha2-macroglobulin, IgG, IgA, and IgM. In another experiment putative terminal galactosyl groups of desialylated glycoproteins in the D-galactose eluate from cirrhotic serum exposed to RCAI-Sephadex were labelled with tritiated borohydride after treatment with galactose oxidase. Subsequent gel electrophoresis showed peaks of radioactivity throughout the area of the gel corresponding to protein molecular weights of the 19 S, 7 S, and 4 S classes. It thus appears that a heterogeneous population of desialylated serum glycoproteins accounts for the inhibition of binding of desialylated glycoprotein to the hepatocyte membrane and that these desialylated glycoproteins are present in small amounts in normal human serum and in greatly increased quantities in serum from patients with cirrhosis.
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PMID:Serum inhibitors of desialylated glycoprotein binding to hepatocyte membranes. 10 Dec 52

A galactose-specific lectin from seeds of Sunn Hemp (Crotalaria juncea) has been purified by fractional precipitation with ammonium sulfate followed by biospecific affinity chromatography and preparative isoelectric focusing. The adsorbent was prepared by coupling galactose to Sepharose 6B activated with divinyl sulfone. The lectin was homogeneous as judged by ultracentrifugation and by electrophoresis in cellulose acetate strips and in polyacrylamide gradient gel. Its isoelectric point is pH 8.8 and the molecular weight is about 120 000. It is a glycoprotein containing 9.8% also carbohydrate (mannose, N-acetyl-D-glucosamine, fucose, and xylose). The lectin contains 3.2 mol Ca2+, 2.2 mol Mg2+ and 0.2 mol Mn2+ per 120 000 g. No sulphur-containing amino acids were detected.
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PMID:A phytohemagglutinin from Sunn hemp seeds (Crotalaria juncea). II. Purification by a high capacity biospecific affinity adsorbent and its physicochemical properties. 90 13

The extracellular matrix of the sea urchin embryo contains a 230 kD homodimeric glycoprotein known as echinonectin (EN). EN contains a cell attachment domain as well as a galactose-specific lectin activity. Cell attachment to EN is differentially regulated in the three primary germ layers, endoderm, ectoderm and mesoderm. Prior to gastrulation all embryonic cells adhere equally to EN-coated substrates, but during gastrulation primary mesenchyme cells lose affinity for EN, ectoderm cells increase their binding to the molecule, and cells of the endoderm maintain a similar or slightly lowered level of binding. The mechanisms governing these adhesive changes and the specific functions they serve in development are not currently understood. They are timed to coincide with distinct morphogenetic events such as primary mesenchyme cell ingression and archenteron formation, suggesting that regulated adhesion to EN plays at least a permissive role in early morphogenesis.
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PMID:The structure and activities of echinonectin: a developmentally regulated cell adhesion glycoprotein with galactose-specific lectin activity. 179 37

The cytoplasmic tubulovesicular and canalicular membranes of gastric parietal cells are intimately involved in hydrochloric acid secretion. To characterise the glycoproteins of these membranes, we examined a panel of lectins for reactivity with parietal cells in paraffin sections of rat, dog and pig stomach. The poly-N-acetyllactosamine-specific lectin from Lycopersicon esculentum (tomato) and from Solanum tuberosum (potato), and the galactose-specific lectin Ricinus communis agglutinin (RCA120), showed strong cytoplasmic binding of parietal cells of all three species, with a pattern indicative of an intracellular membrane network. Binding to parietal cells was confirmed by double-labelling studies with parietal cell auto-antibodies from patients with autoimmune gastritis. Mucous cells and mucin also bound these lectins strongly. Other gastric cell types did not stain with either tomato or potato lectin, but stained weakly with RCA120. Electron-microscopic examination of lectin binding sites using biotinylated tomato lectin or RCA120 and streptavidin-gold, revealed specific binding to the luminal face of parietal cell tubulovesicular and canalicular membranes as well as the contents of mucous cell secretory granules. Tomato lectin and RCA120 reacted by lectin blotting with a major species of apparent molecular weight 60-90 X 10(3) Mr from rat, dog and pig gastric membranes. A tubulovesicular membrane fraction, enriched 10-fold for K(+)-dependent phosphatase activity, was also enriched three-fold for tomato lectin binding as assessed by a solid-phase lectin assay. The 60-90K (K = 10(3) Mr) component, in 125I-labelled detergent extracts of dog tubulovesicular membranes, bound to an affinity support of tomato lectin-Sepharose and was specifically eluted with N,N',N'-triacetylchitotriose. Digestion with N-glycanase collapsed the 60-90K component into a sharp 35K band. We conclude that: (1) a 60-90K membrane glycoprotein localised on the luminal face of tubulovesicles and canaliculi of parietal cells interacts strongly with tomato lectin and RCA120; and (2) the glycoprotein is composed of a 35K core protein glycosylated with N-glycans probably containing poly-N-acetyllactosamine sequences with terminal galactosyl residues. The properties of this 60-90K glycoprotein are identical to a major parietal cell autoantigen recognised by sera of patients with autoimmune gastritis.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Poly-N-acetyllactosamine-specific tomato lectin interacts with gastric parietal cells. Identification of a tomato-lectin binding 60-90 X 10(3) Mr membrane glycoprotein of tubulovesicles. 216 41

Lipophosphoglycan (LPG) of Leishmania is a polymorphic molecule comprising an alkylglycerol anchor, a conserved oligosaccharide core and a species-specific polymer of oligosaccharide repeats jointed by phosphodiester bonds. This molecule, together with the membrane polypeptide gp63, has been implicated as a parasite receptor for host macrophages. To examine the role of LPG in parasite infectivity glycosylation variants of Leishmania major were generated by chemical mutagenesis of a virulent cloned line V121 and variants with modified LPG selected using the galactose-specific lectin Ricinus communis II (RCA II). Twenty RCA II-resistant primary clones were generated. Analysis of LPG profile by immunoblotting using LPG-specific monoclonal and polyclonal antibodies revealed that some of the clones were LPG-deficient. Three clones that did not bind any LPG-specific antibodies but expressed normal levels of the Mr 63,000 glycoprotein (gp63), a second parasite receptor for host, were chosen for detailed studies. All three clones expressed, at least to some extent, a surface molecule which could be labeled by mild periodate oxidation and sodium borotritide and behaved like LPG by hydrophobic interaction chromatography. All clones also bound a well-characterized monoclonal antibody L157 directed to the core oligosaccharide of LPG, but did not bind another monoclonal antibody, CA7AE, to an epitope on a repeating unit shared by Leishmania donovani and L. major LPG. A third monoclonal antibody, 5E6, recognizing LPG on the surface of wild-type V121 promastigotes bound only to RCA II-resistant clone 3A2-C3 and was restricted to an internal structure. The LPG molecule that this clone expressed was a form of LPG by its chromatographic behavior and by its monosaccharide and alkylglycerol composition. Clone 3A2-C3 was the only one to infect mice in vivo and survive in macrophages in vitro, albeit at a much reduced rate compared to wild-type V121 promastigotes. The data suggest that some form of LPG may be necessary to ensure parasite infectivity.
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PMID:Lipophosphoglycan expression and virulence in ricin-resistant variants of Leishmania major. 236 5

The murine Mac-2 protein is a galactose- and IgE-binding lectin secreted by inflammatory macrophages. We describe here the cloning and characterization of a cDNA representing the human homolog of Mac-2 (hMac-2). The amino acid sequence derived from the hMac-2 cDNA indicates that the protein is evolutionarily highly conserved, with 85% of its amino acid residues being similar to those in the murine homolog. This conservation is especially marked in the carboxyl-terminal lectin domain. The amino-terminal half of the protein is less conserved but still contains the repetitive proline-glycine-rich motif seen in the mouse protein. hMac-2 synthesized in vitro is recognized by the M3/38 monoclonal antibody to Mac-2 and binds to the desialylated glycoprotein asialofetuin and to laminin, a major component of basement membranes. These findings are discussed in the context of the potential functions of hMac-2.
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PMID:Molecular cloning of a human macrophage lectin specific for galactose. 240 11

The responsiveness of enterocytes to Escherichia coli heat-labile enterotoxin (LT) was studied in the small intestine of 6- to 7-week-old rats. Dose-effect analysis showed the dose required for a 50% maximal LT-induced secretory response to be at 8 nM. After the well-documented glycolipid GM1 receptor was blocked with the cholera toxin B subunit, LT still activated the second messenger cascade, measured in terms of heightened cellular adenylate cyclase activity, and caused fluid to be secreted into ligated intestinal loops. Furthermore, Scatchard analysis of binding kinetics suggested that LT bound to two receptor sites on the intestinal microvillus membrane. The toxin also bound to delipidated membrane but was competitively inhibited by a galactose-specific lectin, RCA60, suggesting that the additional receptor is a galactoglycoprotein. Western blot analysis of toxin binding to membrane proteins revealed a group of binding components around 85 to 150 kilodaltons. When measured at 2.2 nM LT, approximately 70% of LT-binding activity took place through a high-affinity (Kd1, 0.38 nM) GM1 receptor and 30% of LT-binding activity took place through a low-affinity (Kd2, 3.3 nM) glycoprotein receptor. These results suggest that LT functions through two microvillus membrane receptors in the mature rat small intestine.
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PMID:Host response to Escherichia coli heat-labile enterotoxin via two microvillus membrane receptors in the rat intestine. 267 13

During the last 15 years we have developed two biological systems, with whom it was possible to study the Ca++-dependent and the Ca++-independent adhesion on cellular level. In contrast to cells from other multicellular organisms, cells from the marine sponge Geodia cydonium are provided with Ca++-dependent adhesion mechanisms only. Two different mechanisms have been discovered by us, which were termed primary aggregation and secondary aggregation. In previous reports, we described that two macromolecules (aggregation factor [sAF] and aggregation receptor [AR] are involved in the secondary aggregation of sponge cells. The sAF was bound to a high-molecular-weight particle and was termed aggregation complex. The aggregation complex was shown to consist of two further functional subunits: UDP-glucuronosyltransferase and UDP-beta-D-galactosyltransferase. The AR with a molecular weight of approximately 17,000 was found to be a glycoprotein with D-glucuronic acid as the terminal sugar moiety. Data are presented from in vitro and in vivo experiments with the Geodia system, indicating that cell aggregation and cell separation are controlled first by alteration of the binding capacity of the aggregation receptor and second by an additional molecule (anti-aggregation receptor), which can decrease the interaction between the aggregation factor and the aggregation receptor. Recently we succeeded in the identification and isolation of the primary aggregation factor (pAF) from the same sponge species. This pAF is a glycoprotein that is firmly associated with the cell membrane. The Mr of the native pAF was 36,000; under denatured conditions three protein species were identified in the pAF preparation. We hypothesize that in contrast to the secondary aggregation, the initial aggregation of Geodia cells is mediated by the one-component system, the bivalent and bifunctional pAF. We were also able to dissociate the coral Eunicella cavolinii into single cells. These cells readily formed aggregates of a size of 2,100 micron during incubation in roller tubes: no aggregate formation was observed in non-rotating petri dishes. The formation of aggregates was not influenced by Ca++, urea or trypsin; it was also independent on temperature (4 degrees C to 30 degrees C) and pH (5.5-9.0). The intercellular material of the gorgonian contains a galactose-specific lectin, as determined by double diffusion experiments and haemagglutination inhibition experiments using a series of galacto-glycoconjugates. This lectin converted the aggregation-susceptible cells to aggregation-deficient cells.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The molecular mechanisms of the distinct calcium-dependent aggregation systems in marine sponges and corals. 286 62

Rat anti-mouse monoclonal antibodies (mAb), anti-Mac-1, -2, and -3, directed against macrophage (M phi) glycoprotein surface antigens, were used to demonstrate a tumor-induced shift in peritoneal M phi subpopulations. This study of the tumor-induced shift was approached in two steps. First, to show that separate phenotypic M phi subpopulations existed and second, to show that a shift in these populations was involved in immunosuppression of the host during tumor growth. Endogenous peroxidase activity was examined among normal and tumor-bearing host (TBH) M phi. A significant increase in the number of peroxidase-positive M phi occurred during tumor growth. Indirect immunofluorescence showed a decrease in Mac-2+ cells and an increase in Mac-3+ cells in TBH M phi populations. When the mAb, anti-Mac-1,-2, and -3 were used in the presence of complement (C), they were cytotoxic for M phi and showed differential depletion of normal and TBH M phi. Peroxidase-positive TBH M phi were susceptible to C-mediated lysis by anti-Mac-1 and -3 but not by anti-Mac-2, whereas no direct relationship was observed among normal host M phi. To demonstrate differences between normal and TBH M phi subpopulations, soluble inhibitory factors were examined from mAb plus C-modified M phi populations. Anti-Mac plus C-treated normal and TBH M phi produced supernatants with different regulatory capabilities as assessed in the mixed-lymphocyte reaction (MLR). Anti-Mac-2 plus C treatment significantly reduced the ability of TBH M phi to produce a soluble suppressor(s) but did not alter normal host M phi-derived suppressor production. In contrast, anti-Mac-1 and -3 plus C treatment of normal host M phi significantly reduced suppressor production. In the TBH, however, anti-Mac-1 plus C had no effect, while anti-Mac-3 plus C had only a limited reduction as compared to the normal host. Determination of levels of prostaglandin E2 (PGE2) in M phi supernatants showed that normal host Mac-1+ M phi were involved in down regulation of PGE2 production. This control was missing in the TBH M phi. Mac-2+ M phi were the apparent producers of PGE2 which accounts for the factor-mediated MLR suppression attributed to TBH Mac-2+ M phi. Collectively, these data suggest that tumor-induced aberrations in immunoregulation can in part be attributed to differences in anti-Mac mAb-defined M phi subpopulations.
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PMID:Shifts in macrophage (M phi) surface phenotypes during tumor growth: association of Mac-2+ and Mac-3+ M phi with immunosuppressive activity. 295 65

In previous studies it was shown that a D-galactose-specific lectin, Ricinus communis I (RCA I), does not bind to the plasma membrane of muscle fibres from patients with Duchenne muscular dystrophy (DMD) in contrast to normal muscle. We have now studied RCA I binding to the membranes of developing human fetal muscle in fetuses at 95% risk of DMD (n = 6) and normal controls (n = 5) with a developmental range of 12-20 weeks of gestation. The results were compared to the membrane appearance with conventional ultrastructure. Binding of RCA I to the muscle basement membrane was consistently strong from the early stages of myogenesis, such as in fusing myoblasts/myocytes. RCA I binding to the plasma membrane was weak but detectable in both DMD and normal fetuses at 12-14 weeks of gestation. Both the normal and diseased condition showed an increase of RCA I labelling of the muscle plasma membrane at 15-17 weeks and strong labelling at 18-20 weeks of gestation. No difference was observed in the RCA I localization of normal and diseased human fetal muscle plasma membrane. It is concluded that (a) the plasma membrane in developing fetal muscle undergoes a maturation process between 12 and 20 weeks gestational age leading to an increase in expression of RCA I binding carbohydrate moieties; and (b) that the absence of RCA I binding glycoprotein in mature DMD muscle plasma membrane reflects a change acquired during the course of disease.
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PMID:Binding of Ricinus communis I lectin to developing dystrophic muscle in human fetus. 337 48


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