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)

A galactose-specific lectin isolated from Ricinus communis beans has been covalently coupled to Sepharose 4B activated with cyanogen bromide. The immobilized lectin retains its polysaccharide-binding property. The Sepharose-lectin can be used for the purification of polysaccharides containing terminal nonreducing galactose. Only a small fraction of 'native fetuin' and 'native ceruloplasmin' are retarded on Sepharose-lectin. On analysis it was observed that they had a lower content of sialic acids as compared to the native and unbound glycoproteins (sialated fractions). However, on desialation, fetuin and ceruloplasmin were completely adsorbed to Sepharose-lectin. The asialoglycoproteins interact strongly with Sepharose-lectin as compared to 'partially sialated glycoproteins'. This has been attributed to the exposure of galactose residues of these glycoproteins on enzymatic desialation. These experiments demonstrated that Sepharose-lectin interacts with glycoproteins through their terminal, non-reducing galactose. On the basis of these experiments it is suggested that Sepharose-lectin can be used as an analytical tool for separation of 'fully sialated glycoproteins' from the 'partially sialated glycoproteins'.
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PMID:Affinity chromatography of galactose containing biopolymers using covalently coupled Ricinus communis lectin to Sepharose 4B. 5 50

Two antigenic polysaccharides were extracted from cell walls of the cross-reactive strains Streptococcus mutans AHT (a) and S. mutans B13 (d). The antigens extracted from walls by the hot formamide method, were purified by affinity chromatography on columns containing the galactose-specific lectin from the castor bean and were found to be diheteroglycans consisting of galactose and glucose. Antigenic specificities of both the serotype-specific and the cross-reactive sites on each polymer were studied: the AHT (a) antigen is determined by D-galactose linked 1 leads to 6 to adjacent sugar, the B13 (d) antigen is determined by D-glucose similarly linked to o its neighbor, and the cross-reactive (a--d) site present on both polymers consists of D-galactose linked 1 leads to 6 to a subterminal sugar moiety. Methylation analysis revealed structural similarities between the purified polysaccharides that may reflect the nature of the cross-reactive sites and differences that may reflect the natures of the specific haptenic regions. Based on these studies, a partial hypothetical structural model is proposed.
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PMID:Chemical, immunochemical, and structural studies of the cross-reactive antigens of Streptococcus mutans AHT and B13. 8 15

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

For the first time, the biological role of a lectin in the process of reaggregation of single cells from the same species (marine sponge: Geodia cydonium Jam.) is described. The galactose-specific lectin does not promote aggregation, but prevents the antiaggregation receptor from disaggregating cell clumps. Competition experiments showed that the lectin inactivates the antiaggregation receptor by binding to it, most likely via its terminal galactose residues. The lectin converts reversibly aggregation-deficient cells (carrying functional cell membrane-bound antiaggregation receptor molecules) to aggregation-susceptible cells.
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PMID:Aggregation of sponge cells. Function of a lectin in its homologous biological system. 11 94

The ability of the rat liver to bind and endocytose human asialo-transferrin was investigated in vivo. Asialo-transferrin was separated from incompletely desialylated transferrin and neuraminidase by chromatography before being labelled with (125)I. Plasma radioactivity curves and hepatic radioactivity contents measured over a 1270-fold dose range led to the following observation. At the lowest dose (0.4mug/100g body wt.), the distribution of asialo-transferrin between plasma and liver resembled a reversible reaction reaching equilibrium in approx. 20min. After 35min, 93% of the dose was recovered with the plasma and liver as protein-bound radioactivity. Most of the asialo-transferrin associated with the liver could be displaced by asialo-orosomucoid, indicating that binding of asialo-transferrin to the galactose-specific lectin on the plasma membrane of hepatocytes was not followed by a signal for endocytosis. A range of doses, up to an average of 509.2mug of asialo-transferrin per 100g body wt., resulted in progressive increments in asialo-transferrin catabolism, as evidenced by lower dose recoveries and increased concentrations of non-protein-associated radioactivity in the liver and plasma volume. These observations indicate that binding and endocytosis of human asialo-transferrin by the rat hepatocyte are distinct phenomena. Individual asialo-transferrin molecules, although readily bound by the hepatic lectin, lack either the quantity or spacing of terminal galactose residues necessary for triggering endocytosis. Although endocytosis is induced by several asialo-transferrin molecules acting synergistically, preliminary experiments with asialo-glycopeptides and other substances have so far failed to provide further insight into the chemical basis of the signal for endocytosis.
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PMID:Distinction between binding and endocytosis of human asialo-transferrin by the rat liver. 69 50

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

Plant ribosome-inactivating proteins (RIPs) are N-glycosidases which cleave the N-glycosidic bond of adenine in a specific ribosomal RNA sequence. Most commonly RIPs are single-chain proteins (type 1 RIPs), but some (type 2 RIPs) possess a galactose-specific lectin domain that binds to cell surfaces. The latter RIPs are potent toxins, the best known of which is ricin. RIPs have antiviral and abortifacient activities, and, in a widespread application, can also be linked to antibodies or ligands to form immunotoxins or conjugates specifically toxic to a given type of cell.
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PMID:Ribosome-inactivating proteins from plants: present status and future prospects. 136 84

In addition to their well characterized high affinity immunoglobulin E (IgE) receptors (Fc epsilon RI) mast cells have long been suspected to express undefined Fc receptors capable of binding IgE with low affinity. In this paper, we show that Fc gamma RII and Fc gamma RIII, but not Mac-2, on mouse mast cells and macrophages bind IgE-immune complexes. This binding is efficiently competed by 2.4G2, a monoclonal antibody against the extracellular homologous region of both Fc gamma RII and Fc gamma RIII. Furthermore, IgE-immune complexes bind specifically to Fc gamma RII or Fc gamma RIII transfected into COS-7 cells. The association constants of IgE binding estimated from competition experiments are about 3.1 x 10(5) M-1 for Fc gamma RII, and 4.8 x 10(5) M-1 for Fc gamma RIII. Engagement of Fc gamma RII and Fc gamma RIII with IgE-immune complexes (after blocking access to Fc epsilon RI) or with IgG-immune complexes triggers C57.1 mouse mast cells to release serotonin. This release is inhibited by 2.4G2, and at maximum, reaches 30-40% of the intracellular content, about half of the maximal release (60-80%) obtained after Fc epsilon RI engagement. These data demonstrate that mouse Fc gamma RII and Fc gamma RIII are not isotype specific, and that the binding of IgE-immune complexes to these receptors induces cell activation.
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PMID:Identification of the low affinity receptor for immunoglobulin E on mouse mast cells and macrophages as Fc gamma RII and Fc gamma RIII. 138 73

epsilon BP (for epsilon binding protein) is a M(r) 31,000 S-type animal lectin that binds to IgE and has been identified as the homologue of Mac-2, a macrophage cell-surface marker, as well as the lectins RL-29, CBP35, and L-34. The protein is composed of two domains with the amino-terminal portion containing tandem repeats of nine amino acids and the carboxyl-terminal half containing consensus sequences shared by S-type animal lectins. We determined the genomic map in both rat and mouse and isolated overlapping genomic clones that contain the 5' two-thirds of the murine gene. The remaining portion of the gene was obtained by polymerase chain reaction (PCR) amplification of genomic murine DNA followed by subcloning into plasmid vectors. The epsilon BP gene is composed of six exons separated by five introns. The entire amino-terminal repetitive sequence is contained in exon III, and the carboxyl-terminal domain is encoded by the three succeeding exons (IV, V, VI). The latter three exons correspond well in size and share sequence homology with three exons coding for 14-kDa S-type lectins. The sequence in exon I offers an explanation for the generation of two mRNAs differing only in their 5' untranslated sequences, previously reported in Mac-2 cDNA clones. Using cDNA synthesis and PCR amplification, we determined that two alternative splice sites are used in many different types of cells. This alternative splicing results in different 5' untranslated regions of the murine epsilon BP mRNA.
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PMID:Genomic cloning of the gene for an IgE-binding lectin reveals unusual utilization of 5' untranslated regions. 139 Jul 36

Dot immunoblotting of crude extracts of various aerial parts of birch trees, using patient serum rich in birch pollen IgE, showed IgE-binding activity in leaves, buds, twigs, seeds, bark, and old male catkins. Seed extracts analysed by SDS-PAGE, electroblotting to nitrocellulose and immune detection using isotope-conjugated anti-IgE verified the presence in seeds of an IgE-binding protein of an approximate molecular weight of 12 kD, distinct from the major allergen (molecular weight 17 kD) of Betula verrucosa pollen. The allergen of birch seeds was readily leachable from the seeds. Many of the birch plant part extracts were active in RAST inhibition using birch pollen RAST discs, but showed low potency relative to the allergenicity of birch pollen allergens.
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PMID:Expression of birch pollen-specific IgE-binding activity in seeds and other plant parts of birch trees (Betula verrucosa Ehrh.). 142 64


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