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)

IgE-binding protein (epsilon BP) was originally identified by virtue of its affinity for IgE. It is now known to be a beta-galactoside-binding lectin with the characteristic of an S-type carbohydrate recognition domain. The protein is composed of two domains: the amino-terminal domain consisting of tandem repeats and the carboxyl-terminal domain containing sequences shared by other S-type carbohydrate recognition domains. The amino-terminal domain also contains a number of potential recognition sites for collagenase cleavage. In this study, human epsilon BP was first expressed in Escherichia coli, and the carboxyl-terminal domain (epsilon BP-C) was then generated by collagenase digestion of epsilon BP. By equilibrium dialysis, the association constants of epsilon BP and epsilon BP-C for lactose were found to be similar (6.0 +/- 0.70) x 10(4) M-1 and (4.7 +/- 0.27) x 10(4) M-1, respectively. Both polypeptides contain only one lactose-binding site/molecule. By an assay involving binding of 125I-labeled epsilon BP or epsilon BP-C to solid phase IgE, and inhibition of this binding by saccharides, it was determined that epsilon BP-C retains the saccharide specificity of epsilon BP. Importantly, although unlabeled epsilon BP-C inhibited the binding of the radiolabeled epsilon BP to IgE, unlabeled epsilon BP caused increased binding to IgE, suggesting self-association among epsilon BP molecules. Oligomeric structures resulting from self-association of epsilon BP were confirmed by chemical cross-linking studies. Furthermore, epsilon BP possesses hemagglutination activity on rabbit erythrocytes, whereas epsilon BP-C lacks such activity. Based on these results, we propose a structural model for multivalency of epsilon BP: dimerization or oligomerization of epsilon BP occurs through intermolecular interaction involving the amino-terminal domain.
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PMID:Biochemical and biophysical characterization of human recombinant IgE-binding protein, an S-type animal lectin. 162 16

We report the complete primary and secondary structures of a metastasis-associated Mr 34,000 galactoside-binding lectin. The polypeptide sequence (264 amino acids) was derived from the nucleotide sequence of three overlapping complementary DNA clones isolated from lambda gt11 and lambda gt10 phage libraries of UV-induced murine fibrosarcomas. Striking features of the polypeptide sequence are two distinct regions of beta-sheet and globular structures at the amino and carboxy terminals, respectively. Homology search suggests that the polypeptide is a chimeric gene product formed by fusion of the 5'-end of an Mr approximately 14,000 galactoside-binding lectin with an internal domain of the collagen alpha gene. Enzymatic treatment with collagenase confirmed the presence of a collagen-like structure in the polypeptide. Unexpectedly, the entire sequence is greater than 85% homologous to a rat low affinity IgE-binding protein.
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PMID:Identification of the metastasis-associated, galactoside-binding lectin as a chimeric gene product with homology to an IgE-binding protein. 252 69

Antigen-retaining follicular dendritic cells (FDC) have been identified and studied in sections of lymph nodes and spleen, but studies of these cells in culture have been extremely limited. The purpose of this study was to establish techniques to release these fragile cells from mouse lymph nodes in a viable state and to identify these cells routinely in lymph node cell suspensions. FDC were obtained from passively or actively immunized popliteal lymph nodes of mice injected in the footpads with 125I-labeled human serum albumin (HSA) or horseradish peroxidase (HRP). Lymph nodes were removed 1 hr after the footpads had been injected with collagenase. After another hour of incubation in vitro with collagenase, protease, and deoxyribonuclease, FDC were released by gentle teasing and enriched by centrifugation on a low density bovine serum albumin (BSA) or Percoll gradient. Most FDC with the associated radiolabel floated at densities greater than 1.06 g/ml on BSA or Percoll gradients. Slides of the FDC-enriched fraction were prepared, using a cytobucket which allowed the cells to be affixed to glass slides by centrifugation in a less disruptive manner than by cytocentrifugation. FDC that were air-dried and fixed with 3% glutaraldehyde had a characteristic pink acidophilic cytoplasm after Wright's staining, and had a faintly basophilic euchromatic nucleus frequently with peripherally-clumped chromatin. In addition, these cells were large and irregularly shaped (up to 60 micron long). Fixation of FDC with 0.6% paraformaldehyde/ 0.9% glutaraldehyde on poly-L-lysine-coated slides resulted in a preservation of FDC which made possible visualization of long dendritic processes by Nomarski optics. Antigen presence on the cell surface was confirmed by autoradiography and, in the case of HRP, was also visualized enzymatically using diaminobenzidine. In contrast to resident peritoneal macrophages or some contaminating lymph node macrophages present on the same slides, FDC did not phagocytize opsonized sheep red blood cells (SRBC) or adhere to plastic surfaces although they did form rosettes with opsonized SRBC. Cell marker studies indicated FDC have a distinctive phenotype. They were positive for Ia, Fc receptor, and leukocyte common antigen, but negative for Thy-1, Ly-1, Ly-2, endogenous Ig, Mac-1, Mac-2, Mac-3, and F4/80, and negative to weakly positive for nonspecific esterase. Cultured FDC remained viable and retained radiolabeled antigen-antibody complexes on their surfaces and were significantly enriched for FDC.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Follicular dendritic cells in suspension: identification, enrichment, and initial characterization indicating immune complex trapping and lack of adherence and phagocytic activity. 396 23

A lactose-binding lectin from rat lung (RL-29) and a related lectin from Madin-Darby canine kidney (MDCK) cells have been analyzed with the primary goal of identifying post-translational modifications. The sequences show that RL-29 and the dog lectin are homologues of a lectin designated here as L-29 and elsewhere as CBP-35, epsilon BP, Mac-2, or L-34. RL-29 has a 140-amino-acid COOH-terminal carbohydrate-binding domain, a 20-amino-acid NH2-terminal domain, and an intervening domain consisting of 11 repeating elements rich in Pro, Gly, and Tyr (R-domain). The dog homologue has 14 repeating elements in its R-domain explaining its larger size. The sensitivity of the R-domain to bacterial collagenase allowed us to isolate the NH2-terminal domain and show that the NH2 terminus was blocked by acetylation and, in the accompanying paper (Huflejt, M. E., Turck, C. W., Lindstedt, R., Barondes, S. H., and Leffler, H. (1993) J. Biol. Chem. 268, 26712-26718), that the NH2-terminal domain is phosphorylated. In addition, we unexpectedly found an endogenous component, resembling 92-kDa type IV collagenase, that co-purified with L-29 and slowly digested the R-domain. Hence, L-29 is a substrate for bacterial and tissue collagenases even though the R-domain is non-collagenous. Moreover, the co-purification suggests a non-enzymatic interaction between 92-kDa collagenase and L-29.
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PMID:Primary structure of the soluble lactose binding lectin L-29 from rat and dog and interaction of its non-collagenous proline-, glycine-, tyrosine-rich sequence with bacterial and tissue collagenase. 825 5

The cDNA clone for carbohydrate-binding protein 35 (CBP35) was engineered into the bacterial expression vector pIN III ompA2, which directs the secretion of the expressed protein into the periplasmic space. Recombinant CBP35 was purified from this system, at a level of approximately 50 mg/liter of bacterial culture. Digestion of recombinant CBP35 with collagenase D, followed by purification using saccharide-specific affinity chromatography yielded a M(r) approximately 16,000 polypeptide, corresponding to the COOH-terminal domain (residues 118-264) of the CBP35 polypeptide. This indicates that the COOH-terminal half of CBP35 contains the carbohydrate recognition domain, consistent with its sequence homology to other S-type lectins. The NH2-terminal domain (residues 1-137) was derived by site-directed mutagenesis of the cDNA, in which stop codons are inserted in place of Gly138 and Gly139, and expression of the mutant cDNA in the same pIN III ompA2 system. The purified NH2-terminal domain failed to bind to saccharide-specific affinity resins. Differential scanning calorimetry of rCBP35 and its individual domains yielded transition temperatures of approximately 39 and approximately 56 degrees C for the NH2- and COOH-terminal domains, respectively. Lactose binding by the COOH-terminal domain shifted the transition temperature to 65 degrees C, whereas sucrose failed to yield the same effect. These results suggest that the individual domains of the CBP35 polypeptide are folded independently.
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PMID:Carbohydrate-binding protein 35. I. Properties of the recombinant polypeptide and the individuality of the domains. 832 70

A galactoside-binding lectin (hL-31) containing a collagen-like sequence was identified in human tumor cells. It was found to be the homologue of the IgE-binding protein, the macrophage cell-surface Mac-2 antigen, and the murine CBP35, RL-29, and mL-34 lectins. Here we report on the expression in Escherichia coli and functional analysis of recombinant hL-31 (rhL-31). The rhL-31 was purified in one step through an asialofetuin affinity column. The rhL-31 was reactive to anti-lectin antibodies and retained its lactose-dependent hemagglutination of trypsin-treated glutaraldehyde-fixed rabbit erythrocytes. The rhL-31 elutes from an affinity column as a 31-kDa monomer and undergoes homodimerization at relatively high protein concentrations, comparable to those used to mediate hemagglutination. Electron microscopy showed that the rhL-31 appears as a Y-shaped structure. Lactoperoxidase-catalyzed iodination of murine tumor cell-surface proteins followed by collagenase treatment revealed that the lectin is probably a peripheral membrane protein whereby both the amino and the carboxy termini are exposed on the outer cell membrane. These results point to the membrane disposition and orientation of the lectin and suggest a mechanism for a structure-function relationship of lectin activity.
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PMID:Structure-function relationship of a recombinant human galactoside-binding protein. 847 70

Protein (lectin)-carbohydrate (cellular glycoconjugate) recognition is operative in biochemical information transfer. Galectins constitute a family of endogenous galactoside-binding lectins with conserved features in the binding site. The members of this lectin category are assumed to be involved in cell adhesion and growth regulation. To assess to what extent the different modes of binding-site presentation and/or carbohydrate fine-specificities will affect aspects of galectin behavior, homodimeric cross-linking galectin-1 and monomeric chimeric galectin-3, with its collagenase-sensitive stalk linked to the carbohydrate-recognition domain, were investigated. Cell-surface expression of the two galectins and accessible galectin-binding sites on various tumor cell lines was ascertained by FACScan analysis. In particular, ligand accessibility for the two galectins differed for the tested cell line types. Binding of tumor cells to laminin and plasma or placental fibronectin was generally reduced by treatment of cells or matrix with galectins. Galectin-3 was more efficient than galectin 1 at impairing laminin's potency as matrix. Cell binding of galectin-1, on the other hand, proved on average more effective for blocking cell association to fibronectins after its preincubation with cell suspensions. Differences were also apparent in the biodistribution of the galectins, where an avian homolog of galectin- served as the control to distinguish effects of spatial and sugar-binding features. Histopathological analysis of lymph-node-negative and -positive breast and colorectal carcinomas (n = 180 including 60 metastatic lesions) indicated a correlation of either increased galectin-1 binding and reduced galectin-3 expression or reduced binding of both galectins with the occurrence of lymph node lesions. Together with data on the heparin-binding lectin, revealing reduced expression to be associated with a positive lymph-node status in the breast cancer group, these results can be interpreted to reflect cell-type-dependent requirements of galectin ligand presentation during the metastatic cascade. By introducing mammalian lectins to lectin-histochemical studies, the detection of quantitative differences in glycosylation brings an understanding of its cell biological significance one step closer.
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PMID:Galectins-1 and -3 and their ligands in tumor biology. Non-uniform properties in cell-surface presentation and modulation of adhesion to matrix glycoproteins for various tumor cell lines, in biodistribution of free and liposome-bound galectins and in their expression by breast and colorectal carcinomas with/without metastatic propensity. 1048 Mar 38

Galectin-3 is a member of the beta-galactoside-binding protein family shown to be involved in tumor progression and metastasis. It has a unique primary structure consisting of three domains: a 12-amino acid leader sequence containing a casein kinase I serine phosphorylation site, which is preceded by a collagenase-sensitive Pro-Gly-rich motif, and a COOH-terminal half encompassing the carbohydrate-binding site. To study the functional role of the unusual leader sequence of galectin-3, a mutant cDNA that causes an 11-amino acid deletion in the NH2-terminal region was generated and expressed in galectin-3-null BT-549 human breast carcinoma cells. Deletion of the NH2 terminus resulted in abolition of the secretion of truncated galectin-3, loss of nuclear localization, and reduced carbohydrate-mediated functions compared with the wild-type protein. When green fluorescent protein was fused to the galectin-3 leader sequence and transiently transfected into BT-549 cells, the uniform cellular distribution of native green fluorescent protein was changed mainly to a nuclear pattern. To further investigate whether the functional changes observed in a galectin-3 with the 11 NH2-terminal amino acids deleted were due to loss of phosphorylation at Ser6, two point mutations were created at this serine: Ser6-->Ala and Ser6-->Glu. No obvious difference was observed in cellular localization between wild-type and Ser6-mutated transfectants. These results suggest a structural role for the NH2 terminus leader motif of galectin-3 in determining its cellular targeting and biological functions independent of phosphorylation.
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PMID:The NH2 terminus of galectin-3 governs cellular compartmentalization and functions in cancer cells. 1062 18

A model structure (Henrick,K., Bawumia,S., Barboni,E.A.M., Mehul,B. and Hughes, R.C. (1998) Glycobiology:, 8, 45-57) of the carbohydrate recognition domain (CRD, amino acid residues 114-245) of hamster galectin-3 has been extended to include N-terminal domain amino acid residues 91-113 containing one of the nine proline-rich motifs present in full-length hamster galectin-3. The modeling predicts two configurations of the N-terminal tail: in one the tail turns toward the first (SI) and last (S12) beta-strands of the CRD and lies at the apolar dimer interface observed for galectins -1 and -2. In the second folding arrangement the N-terminal tail lies across the carbohydrate-binding pocket of the CRD where it could participate in sugar-binding: in particular tyrosine 102 and adjacent residues may interact with the partly solvent exposed nonreducing N-acetylgalactosamine and fucose substituents of the A-blood group structure GalNAcalpha1,3 [Fucalpha1,2]Galbeta1,4GlcNAc-R. Binding studies using surface plasmon resonance of a recombinant fragment Delta1-93 protein containing residues 94-245 of hamster galectin-3 and a collagenase-derived fragment Delta1-103 containing residues 104-245, as well as alanine mutagenesis of residues 101-105 in Delta1-93 protein, support the prediction that Tyr102 and adjacent residues make significant contributions to oligosaccharide binding.
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PMID:Molecular modeling and mutagenesis studies of the N-terminal domains of galectin-3: evidence for participation with the C-terminal carbohydrate recognition domain in oligosaccharide binding. 1108 12

Toxic liver injury causes necrosis and fibrosis, which may lead to cirrhosis and liver failure. Despite recent progress in understanding the mechanism of liver fibrosis, our knowledge of the molecular-level details of this disease is still incomplete. The elucidation of networks and pathways associated with liver fibrosis can provide insight into the underlying molecular mechanisms of the disease, as well as identify potential diagnostic or prognostic biomarkers. Towards this end, we analyzed rat gene expression data from a range of chemical exposures that produced observable periportal liver fibrosis as documented in DrugMatrix, a publicly available toxicogenomics database. We identified genes relevant to liver fibrosis using standard differential expression and co-expression analyses, and then used these genes in pathway enrichment and protein-protein interaction (PPI) network analyses. We identified a PPI network module associated with liver fibrosis that includes known liver fibrosis-relevant genes, such as tissue inhibitor of metalloproteinase-1, galectin-3, connective tissue growth factor, and lipocalin-2. We also identified several new genes, such as perilipin-3, legumain, and myocilin, which were associated with liver fibrosis. We further analyzed the expression pattern of the genes in the PPI network module across a wide range of 640 chemical exposure conditions in DrugMatrix and identified early indications of liver fibrosis for carbon tetrachloride and lipopolysaccharide exposures. Although it is well known that carbon tetrachloride and lipopolysaccharide can cause liver fibrosis, our network analysis was able to link these compounds to potential fibrotic damage before histopathological changes associated with liver fibrosis appeared. These results demonstrated that our approach is capable of identifying early-stage indicators of liver fibrosis and underscore its potential to aid in predictive toxicity, biomarker identification, and to generally identify disease-relevant pathways.
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PMID:Systems level analysis and identification of pathways and networks associated with liver fibrosis. 2538 Jan 36


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