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

A cDNA encoding the Mac-2 antigen, a surface marker highly expressed by thioglycollate-elicited macrophages, has been cloned by immunoscreening of a lambda gt11-P388D1 expression library. The nucleotide sequence of the cDNA is identical to that of carbohydrate-binding protein 35, a galactose-specific lectin found in fibroblasts and highly homologous to a rat IgE-binding protein from basophilic leukemia cells. The in vitro synthesized Mac-2 protein displayed the expected carbohydrate- and IgE-binding properties. By pulse-chase analysis and subcellular fractionation studies, the Mac-2 protein was found in the cytosol but was also seen to accumulate in the extracellular medium. The latter finding was surprising in view of the fact that the cDNA did not encode a signal peptide or transmembrane domain. An alternatively spliced cDNA with the potential to encode a NH2 terminally extended Mac-2 protein with a stretch of hydrophobic amino acids at its NH2 terminus was also found, but it is not clear whether it is the source of the extracellular Mac-2. Possible functions for the Mac-2 protein based on its lectin- and IgE-binding properties are discussed.
 ...
PMID:The Mac-2 antigen is a galactose-specific lectin that binds IgE. 258 31

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.
 ...
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.
 ...
PMID:Carbohydrate-binding protein 35. I. Properties of the recombinant polypeptide and the individuality of the domains. 832 70

The murine Mac-2 gene is composed of six exons dispersed over 10.5 kilobases. S1 nuclease mapping showed multiple transcription initiation sites, clustered within a 30-base pair region. Sequence analysis revealed that a consensus initiator sequence is located in this area which lacks a TATA motif. The untranslated first exon contains an alternative splice donor site, confirming the existence of two cDNA species with the potential to encode proteins differing at their NH2 termini. In vitro expression and translocation experiments demonstrate that both of the alternatively spliced variants of Mac-2 encode proteins which lack a functional signal peptide. Subcellular fractionation studies indicate that most of the Mac-2 protein is present in the cytosol. These results support the view that Mac-2 is exported from the cell by an unusual mechanism which does not depend on the presence of a signal peptide.
 ...
PMID:Structure of the murine Mac-2 gene. Splice variants encode proteins lacking functional signal peptides. 850 79

Parathyroid hormone (PTH) and PTH-related protein (PTHrP) exert their calciotropic activities by binding to a specific seven-transmembrane-helix-containing G protein-coupled receptor mainly located in bone and kidney cells. In order to map in detail the nature of hormone-receptor interaction, we are employing 'photoaffinity scanning' of the bimolecular interface. To this end, we have developed photoreactive benzophenone (BP)-containing PTH analogs which can be specifically and efficiently cross-linked to the human (h) PTH/PTHrP receptor. In this report, we describe the photocross-linking of a BP-containing PTH antagonist, [Nle8,18,D-2-Nal12,Lys13(epsilon-BP),2-Nal23,Tyr34]bPT H(7-34)NH2 (ANT) to the recombinant hPTH/PTHrP receptor stably expressed in human embryonic kidney cells (HEK-293, clone C-21). This photoreactive antagonist has high affinity for the hPTH/PTHrP receptor and inhibits agonist-induced cyclase activity and intracellular calcium release. The photo-induced cross-linking of the radioiodinated antagonist (125I-ANT) to the recombinant hPTH/PTHrP receptor followed by SDS-PAGE analysis reveals a single radiolabeled band of approximately 85kDa, similar to that observed after cross-linking of a radioiodinated BP-containing agonist. The formation of this covalent 125I-ANT - hPTH/PTHrP receptor conjugate is competed dose-dependently by a variety of unlabelled PTH- and PTHrP-derived agonists and antagonists. This is the first report of a specific and efficient photocross-linking of a radioiodinated PTH antagonist to the hPTH/PTHrP receptor. Therefore, it provides the opportunity to study directly the nature of the bimolecular interaction of PTH antagonist with the hPTH/PTHrP receptor.
 ...
PMID:Development of a photoreactive parathyroid hormone antagonist to probe antagonist-receptor bimolecular interaction. 1046 46

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.
 ...
PMID:The NH2 terminus of galectin-3 governs cellular compartmentalization and functions in cancer cells. 1062 18

In search of specific and highly selective sugar clusters for cell receptors, such as membrane lectins, various disaccharides were coupled to small peptide cores through an amide bond. In a first step, the reducing disaccharides, i.e. lactose and three different dimannoses, were converted into glycosyl-pyroglutamyl-beta-alanine derivatives. The free carboxylic group of these conjugates was then coupled to the alpha and epsilon amino groups of the core peptide (Lys( n )-Ala-Cys-NH2) with n =1 to 5, with complete substitution leading to homogeneous glycoclusters. The thiol group of the cysteine residue was used to tag the glycosylated oligolysines upon reaction with fluorescein iodoacetamide. The affinity of these glycoclusters towards two plant lectins was assessed by surface plasmon resonance. The selectivity of their cell uptake was investigated by flow cytometry using two types of cells: a human hepatoma cell line (HepG2 cells) expressing the plasma membrane galactose-specific lectin, and monocyte-derived dendritic cells expressing the plasma membrane mannose-specific lectin. The glycoclusters containing four or five disaccharides were shown to bind plant lectins and cell surface membrane lectins with a narrow selectivity and with a high affinity.
 ...
PMID:Oligolysine-based saccharide clusters: synthesis and specificity. 1211 48

Fluorescence labeling of naturally occurring saccharides provides a tool for studying lectins. A practical and efficient two-step protocol for fluorescence labeling of reducing sugars without disrupting their pyranose structure has been developed, consisting of generation of the amino sugar using NH(4)HCO(3)(s)/NH(3)(aq, concentrated) followed by BOP-mediated acylation with derivatives of 5- or 6-carboxyfluorescein. The acylated conjugates were subsequently run against galectins-1, -3, and -8, beta-galactoside recognizing lectins of current interest, in a fluorescence polarization binding assay. Upon analyzing a collection of isomerically pure 5- and 6-carboxyfluorescein derivatives with different tether lengths, we found that conjugates based on 5-carboxyfluorescein gave significantly better results than the ones based on 6-carboxyfluorescein and that galectins-1 and -8 favored conjugates with different tether lengths than did galectin-3. The results show that fluorescence labeling can be chemically tuned to find optimal probes for individual galectins but also probes interacting well with many galectins.
 ...
PMID:Efficient and expedient two-step pyranose-retaining fluorescein conjugation of complex reducing oligosaccharides: galectin oligosaccharide specificity studies in a fluorescence polarization assay. 1462 46

Galectin-3 (gal-3), a pleiotrophic protein, is an important regulator of tumor metastasis, which like beta-catenin shuttles between the nucleus and the cytosol in a phosphorylation-dependent manner. We report herein that beta-catenin stimulation of cyclin D1 and c-myc expression is gal-3 dependent. Gal-3 binds to beta-catenin/Tcf complex, colocalizes with beta-catenin in the nucleus, and induces the transcriptional activity of Tcf-4 as determined by the TOP/FOPFLASH reporter system. We have identified the beta-catenin-gal-3-binding sequences, which are in the NH2 and COOH termini of the proteins encompassing amino acid residues 1 to 131 and 143 to 250, respectively. These data indicate that gal-3 is a novel binding partner for beta-catenin involved in the regulation of Wnt/beta-catenin signaling pathway.
 ...
PMID:Galectin-3, a novel binding partner of beta-catenin. 1537 39

IFN-gamma plays a role in the response to melanoma indirectly through its effect on the immune system and directly through its antiproliferative and proapoptotic effects on melanoma cells. To understand the molecular basis for the direct antimelanoma effect of IFN-gamma, we studied IFN-induced changes in gene expression and signaling among three human melanoma cell lines (DM6, DM93, and 501mel). These were resistant to the antimelanoma effect of IFN-alpha, and only DM6 cells exhibited growth inhibition and apoptosis with IFN-gamma. Through DNA microarray analysis, we found that the antimelanoma effect of IFN-gamma in DM6 was associated with the down-regulation of multiple genes involved in G-protein signaling and phospholipase C activation (including Rap2B and calpain 3) as well as the down-regulation of genes involved in melanocyte/melanoma survival (MITF and SLUG), apoptosis inhibition (Bcl2A1 and galectin-3), and cell cycling (CDK2). The antimelanoma effect of IFN-gamma was also associated with the up-regulation of the proapoptotic dependence receptor UNC5H2 and the Wnt inhibitor Dkk-1. Whereas both IFNs were able to activate Stat1 in all cell lines, the delayed activation of the extracellular signal-regulated kinase, p38, and c-Jun NH2-terminal kinase mitogen-activated protein kinases occurred only in DM6 with IFN-gamma, and the effect of IFN-gamma on cell growth and survival as well as gene expression in DM6 was dependent on the coordinate activation of MEK1 and p38. These findings provide new insights into the signaling events and gene expression changes associated with growth inhibition and apoptosis in melanoma and may thereby assist in identifying new targets for the treatment of melanoma.
 ...
PMID:Gene expression changes and signaling events associated with the direct antimelanoma effect of IFN-gamma. 1620 58


1 2 Next >>