Showing papers on "Galectin published in 1997"
TL;DR: Galectin-9 is a new member of the galectin gene family and has a unique intestinal isoform, found to be widely distributed, i.e. in liver, small intestine, thymus > kidney, spleen, lung, cardiac and skeletal muscle > reticulocyte, brain.
325 citations
TL;DR: Findings indicate that galectin-9, a developmentally regulated lectin, plays a role in thymocyte-epithelial interactions relevant to the biology of the thymus.
Abstract: Galectin-9, a beta-galactoside binding lectin, has recently been isolated from murine embryonic kidney In this study, its biological functions and expression in embryonic, newborn, and adult mice tissues were investigated By Northern blot analyses, it was found widely distributed and its expression was developmentally regulated In situ hybridization studies revealed an accentuated expression of galectin-9 in liver and thymus of embryonic mice In postnatal mice, antigalectin-9 immunoreactivity was observed in various tissues, including thymic epithelial cells The high expression of galectin-9 in the thymus led us to investigate its role in the clonal deletion of thymocytes Fusion proteins were generated, which retained lactose-binding activity like the endogenous galectin-9 Galectin-9, at 25 microM concentration, induced apoptosis in approximately 30% of the thymocytes, as assessed by terminal deoxytransferase-mediated dUTP nick end labeling method The apoptotic effect was dose dependent and lactose inhibitable At higher concentrations, it induced homotypic aggregation of the thymocytes Electron microscopy revealed approximately 60% of the thymocytes undergoing apoptosis in the presence of galectin-9 By immunofluorescence microscopy, some of the thymocytes undergoing apoptosis had plasmalemmal bound galectin-9 Galectin-9 failed to induce apoptosis in hepatocytes Taken together, these findings indicate that galectin-9, a developmentally regulated lectin, plays a role in thymocyte-epithelial interactions relevant to the biology of the thymus
279 citations
TL;DR: Using autologous serum for the immunoscreening of a cDNA expression library derived from tissue involved by Hodgkin's disease, a new 36-kDa protein with the characteristics of galectins (S-type lectins) was detected, and this novel galactoside binding protein galectin-9 is suggested to be designated.
256 citations
TL;DR: Galectin 3 expression is down-regulated in the initial stages of neoplastic progression, whereas a dissociated cytoplasmic expression increases in later phases of tumor progression.
211 citations
TL;DR: It is shown here that hamster galectin 3 overexpressed in transfected cos-7 cells is secreted at a very low rate indicating that movement of cytoplasmic galactoside-binding protein to plasma membrane domains is a rate limiting step in lectin secretion.
Abstract: Galectin 3, a 30 kDa galactoside-binding protein distributed widely in epithelial and immune cells, contains no signal sequence and is externalized by a mechanism independent of the endoplasmic reticulum (ER)-Golgi complex. We show here that hamster galectin 3 overexpressed in transfected cos-7 cells is secreted at a very low rate. A chimaera of galectin 3 fused to the N-terminal acylation sequence of protein tyrosine kinase p56(lck), Nt-p56(lck)-galectin 3, which is myristoylated and palmitoylated and rapidly transported to plasma membrane domains, is efficiently released from transfected cells indicating that movement of cytoplasmic galectin 3 to plasma membrane domains is a rate limiting step in lectin secretion. N-terminal acylation is not sufficient for protein secretion since p56(lck) and the chimaera Nt-p56(lck)-CAT are not secreted from transfected cells. The amino-terminal half of galectin 3 is sufficient to direct export of a chimaeric CAT protein indicating that part of the signal for plasma membrane translocation lies in the N-terminal domains of the lectin. Immunofluorescence studies show that Nt-p56(lck)-galectin 3 aggregates underneath the plasma membrane and is released by membrane blebbing. Vesicles of low buoyant density isolated from conditioned medium are enriched in galectin 3. The lectin is initially protected from exogenous collagenase but is later released in soluble protease-sensitive form from the lectin-loaded vesicles. Using murine macrophages, which secrete their endogenous galectin 3 at a moderate rate especially in the presence of Ca2+-ionophores, we were also able to trap a galectin 3-loaded vesicular fraction which was released into the culture supernatant.
190 citations
TL;DR: Nuclear galectins exhibit functional redundancy in their splicing activity and partition, at least partially, in the nucleoplasm with another known splicing factor.
Abstract: Galectins are a family of beta-galactoside-binding proteins that contain characteristic amino acid sequences in the carbohydrate recognition domain (CRD) of the polypeptide. The polypeptide of galectin-1 contains a single domain, the CRD. The polypeptide of galectin-3 has two domains, a carboxyl-terminal CRD fused onto a proline- and glycine-rich amino-terminal domain. In previous studies, we showed that galectin-3 is a required factor in the splicing of nuclear pre-mRNA, assayed in a cell-free system. We now document that (i) nuclear extracts derived from HeLa cells contain both galectins-1 and -3; (ii) depletion of both galectins from the nuclear extract either by lactose affinity adsorption or by double-antibody adsorption results in a concomitant loss of splicing activity; (iii) depletion of either galectin-1 or galectin-3 by specific antibody adsorption fails to remove all of the splicing activity, and the residual splicing activity is still saccharide inhibitable; (iv) either galectin-1 or galectin-3 alone is sufficient to reconstitute, at least partially, the splicing activity of nuclear extracts depleted of both galectins; and (v) although the carbohydrate recognition domain of galectin-3 (or galectin-1) is sufficient to restore splicing activity to a galectin-depleted nuclear extract, the concentration required for reconstitution is greater than that of the full-length galectin-3 polypeptide. Consistent with these functional results, double-immunofluorescence analyses show that within the nucleus, galectin-3 colocalizes with the speckled structures observed with splicing factor SC35. Similar results are also obtained with galectin-1, although in this case, there are areas of galectin-1 devoid of SC35 and vice versa. Thus, nuclear galectins exhibit functional redundancy in their splicing activity and partition, at least partially, in the nucleoplasm with another known splicing factor.
151 citations
120 citations
TL;DR: The results demonstrate not only that the galectin gene family is evolutionarily much older than previously realized but also that fine specificity for complex saccharide structures has been conserved.
117 citations
TL;DR: The data demonstrate a specific pattern of galectin-1 and galECTin-3 expression in trophoblastic tissue, and suggest these lectins could contribute to cell-cell and cell matrix interactions of trophoblast during placentation.
99 citations
TL;DR: Galectin-4 is secreted by a nonclassical pathway, and the brush border enzymes represent a novel class of natural ligands for a member of the galectin family.
Abstract: Detergent-insoluble complexes prepared from pig small intestine are highly enriched in several transmembrane brush border enzymes including aminopeptidase N and sucrase-isomaltase, indicating that they reside in a glycolipid-rich environment in vivo. In the present work galectin-4, an animal lectin lacking a N-terminal signal peptide for membrane translocation, was discovered in these complexes as well, and in gradient centrifugation brush border enzymes and galectin-4 formed distinct soluble high molecular weight clusters. Immunoperoxidase cytochemistry and immunogold electron microscopy showed that galectin-4 is indeed an intestinal brush border protein; we also localized galectin-4 throughout the cell, mainly associated with membraneous structures, including small vesicles, and to the rootlets of microvillar actin filaments. This was confirmed by subcellular fractionation, showing about half the amount of galectin-4 to be in the microvillar fraction, the rest being associated with insoluble intracellular structures. A direct association between the lectin and aminopeptidase N was evidenced by a colocalization along microvilli in double immunogold labeling and by the ability of an antibody to galectin-4 to coimmunoprecipitate aminopeptidase N and sucrase-isomaltase. Furthermore, galectin-4 was released from microvillar, right-side-out vesicles as well as from mucosal explants by a brief wash with 100 mM lactose, confirming its extracellular localization. Galectin-4 is therefore secreted by a nonclassical pathway, and the brush border enzymes represent a novel class of natural ligands for a member of the galectin family. Newly synthesized galectin-4 is rapidly "trapped" by association with intracellular structures prior to its apical secretion, but once externalized, association with brush border enzymes prevents it from being released from the enterocyte into the intestinal lumen.
95 citations
TL;DR: The differential expression of these two lectins suggests that they could participate in the complex processes of tissue differentiation, and constitutes the first demonstration of galECTin‐1 and galectin‐3 during human embryogenesis.
Abstract: Development of complex organisms requires specific temporospatial differentiation and expression of the correct phenotype through activation of a variety of genes. Galectins are mammalian lectins able to interact with various extracellular matrix glycoconjugates and have been implicated in several biological events including cell attachment, differentiation, apoptosis, embryogenesis, and cancer invasion and metastasis. In this study, we have examined the expression of galectin-1 and galectin-3 during human first trimester embryogenesis using immunohistochemistry and Western blotting. Variable amounts of galectin-1 and galectin-3 were detected in all tissue protein extracts. Galectin-1 expression was demonstrated in the connective tissue and derived tissues such as smooth and striated muscle cells, and in some epithelia, such as in the basal layers of the skin after 14 weeks and in the epithelial cells of the gonads. Galectin-3 was detected mainly in epithelia, such as the skin, epithelial lining of the digestive and respiratory tract, and urothelium and excretory tubes of the kidney, but also in the myocardial cells, in the peripheral and preossifying hypertrophic chondrocytes, and in the notochord and in the liver. Our study constitutes the first demonstration of galectin-1 and galectin-3 during human embryogenesis. The differential expression of these two lectins suggests that they could participate in the complex processes of tissue differentiation.
TL;DR: The localization of galectin-4 suggests a role in cell adhesion which is also supported by the ability of immobilized recombinant galectIn-4 to stimulate adhesion of T84 cells.
TL;DR: Induction of apoptosis by a beta-galactoside-binding protein highlights a potentially novel mechanism for regulating the immune response and points to a rational basis for the postulated immunomodulatory properties of this protein family.
Abstract: Beta-galactoside-binding lectins or galectins are a family of closely related carbohydrate-binding proteins which functions still remain to be elucidated. Several evidence suggest they could play a role in different biological processes, such as cell growth regulation and immunomodulation. In the present study we report that affinity-purified CLL-I (chicken lactose lectin-I), an acidic 16-kDa galectin exhibits specific growth regulatory properties. Con A-stimulated rat spleen mononuclear cells showed a marked dose-dependent growth inhibition upon incubation with the galectin protein. Cell growth arrest was highly prevented by galectin-specific sugars. In addition, biochemical, cytofluorometrical, and morphological evidence are also provided to show that these inhibitory properties are related to a positive control in the apoptotic threshold of spleen mononuclear cells. Flow cytometric analysis showed a dose- and time-dependent increase of cells with hypodiploid DNA content upon exposure to CLL-I. Moreover, cells treated with CLL-I displayed the typical ultrastructural changes compatible with apoptosis, mainly chromatin condensation and margination along the inner surface of the nuclear envelope. Finally, the highly characteristic "ladder" pattern of DNA fragmentation into oligonucleosome-length fragments of approximately 180-200 bp could be found within 6 h of cell culture with CLL-I, mainly in the T cell-enriched population. Induction of apoptosis by a beta-galactoside-binding protein highlights a potentially novel mechanism for regulating the immune response and points to a rational basis for the postulated immunomodulatory properties of this protein family.
TL;DR: It is hypothesized that this glycan with its terminal alpha1-3 linked GalNAc determinant might represent the first natural cytoplasmic ligand for endogenous galectins-3 detected so far.
Abstract: We report on a novel posttranslational modification of cytoplasmic proteins. Presented evidences suggest that cytokeratins are bound in vitro by mammalian galectin-3 and the galectins from the sponge Geodia cydonium via their type II carbohydrate recognition domains, whose highest binding affinity is directed towards terminal alpha-N-acetylgalactosamine-bearing glycans with the general sequence GalNAcalpha1-3Gal(NAc)beta. Specificity analyses and the characterization of the critical sugar residue on cytokeratins for galectin binding were done with cytochemical and biochemical methods using various plant and animal lectins. Binding of GalNAc-specific lectins was saturable, sensitive to mild periodate oxidation, inhibitable by glycoconjugates carrying terminal GalNAc, and abolished after treatment of the cytokeratins with alpha-N-acetylgalactosaminidase. Binding to bacterially expressed recombinant cytokeratins did not exceed background binding. The presence of GalNAc residues on highly purified cytokeratins from MCF-7 and HeLa SS6 cells was confirmed by sugar composition analyses using gas chromatography/mass spectrometry. This novel posttranslational modification was not restricted to cytokeratins of MCF-7 cells, but did also occur in all of 9 other examined human carcinoma cell lines and in a normal human mammary epithelial cell line. From these cytochemical and biochemical in vitro studies we hypothesize that this glycan with its terminal alpha1-3 linked GalNAc determinant might represent the first natural cytoplasmic ligand for endogenous galectins-3 detected so far.
TL;DR: Comparing the affinity of N32, Nh, and Ch for asialofetuin-Sepharose by frontal affinity chromatography suggests that the two CRDs in this tandem-repeat galectin have different sugar binding properties and that the 32-kDa galectionin may serve as a heterobifunctional crosslinker.
Abstract: Some properties of recombinant proteins derived from the 32-kDa galectin isolated from the nematode Caenorhabditis elegans, which lectin is composed of two tandemly repeated homologous domains [Hirabayashi et al. (1992) J. Biol. Chem. 267, 15485], were studied in order to elucidate the function of this unique polypeptide architecture. We expressed the whole molecule (N32), the N-terminal lectin domain (Nh), and the C-terminal lectin domain (Ch) in Escherichia coli using the expression vector pET21a. All of the recombinant proteins were bound by asialofetuin-Sepharose. CD spectra of the recombinant proteins indicated all of them to be rich in beta-structure and properly refolded. Gel filtration on an HPLC column suggested that all of them existed as monomers. Neither Nh nor Ch seemed to form dimers, in contrast to vertebrate proto-type galectins. Only N32 showed hemagglutination activity towards trypsinized rabbit erythrocytes. Comparison of the affinity of N32, Nh, and Ch for asialofetuin-Sepharose by frontal affinity chromatography [Kasai et al. (1986) J. Chromatogr. 376, 33] showed that Ch has 7-fold weaker affinity than N32, and Nh proved to have still weaker affinity. Since the Asn residue in the CRD (carbohydrate recognition domain), which is conserved in all other galectins, is substituted by Ser in the case of Nh, these data suggest that the two CRDs in this tandem-repeat galectin have different sugar binding properties and that the 32-kDa galectin may serve as a heterobifunctional crosslinker.
TL;DR: The structural basis for carbohydrate recognition by some of these lectins is clarified, and the necessity of combining multiple CRDs in a native lectin molecule in order to increase the affinity for multiple ligands is of great importance physiologically.
TL;DR: Rec recombinant galectin-1 was produced and its binding sites on tissue sections of rat GI tract were surveyed, raising the possibility that some GI tract galectins known to be secreted by the epithelia may recognize these glycoconjugates and crosslink them into a macromolecular mass.
Abstract: Rat gastrointestinal (GI) tract is rich source of galectins, a family of mammalian galactoside-binding lectins. To determine which tissue component is the relevant glycoconjugate ligand for the galectins, we produced recombinant galectin-1 and surveyed its binding sites on tissue sections of rat GI tract. Mucin and epithelial surface glycocalyces of both gastric and intestinal mucosa were intensely stained. This finding raises the possibility that some GI tract galectins known to be secreted by the epithelia may recognize these glycoconjugates and crosslink them into a macromolecular mass. This galectin-ligand complex may play a role in protecting the epithelial surface against luminal contents such as gastric acid, digestive enzymes, and foreign organisms.
TL;DR: The results suggest the importance of monocyte adhesion to the biomaterial surface for their development into macrophages and further non-self-recognition of the implanted device.
TL;DR: This review focuses on recent reports concerning the contribution of N-glycosylation of tumor cell adhesion molecules and some selected membrane proteins in the tumor invasion and metastasis.
Abstract: Metastasis accounts for most of deaths caused by cancer. The increasing body of evidence suggests that changes in N-glycosylation of tumor cell proteins such as increased branching, increased sialylation, polysialylation, decreased fucosylation, enhanced formation of Lewis X and sialyl Lewis X antigens are among important factors determining metastatic potential of tumor cell. Most of the adhesion proteins, e.g., integrins, members of immunoglobulin superfamily, and cadherins are heavily N-glycosylated. The other proteins involved in adhesion, like galectins and type-C selectins, recognize N-glycans as a part of their specific ligands. In this review we focus on recent reports concerning the contribution of N-glycosylation of tumor cell adhesion molecules and some selected membrane proteins in the tumor invasion and metastasis.
TL;DR: This work demonstrates that the intron-exon structure of the gene encoding CLC is analogous to those encoding the galectins, and isolated CLC beta-galactoside binding sites from both orangutan and murine genomic DNAs.
Journal Article•
TL;DR: The potential value of combined monitoring of the lectin and its potential in vivo ligands to contribute to eventually unravel organ-related function(s) of a tissue lectin is emphasized.
Abstract: The display of cellular oligosaccharide chains is known to undergo marked developmental changes, as monitored histochemically with plant lectins. In conjunction with endogenous lectins respective ligand structures may have a functional role during fetal development. The assumption of a recognitive, functionally productive interplay prompts the study of the expression of a tissue lectin and of lectin-reactive glycoconjugates concomitantly. Focusing on common beta-galactosides as constituents of oligosaccharide chains and the predominant member of the family of galectins in mammals, namely galectin-1, the question therefore is addressed as to whether expression of lectin and lectin-reactive glycoconjugates exhibits alterations, assessed in three morphologically defined fetal stages and in adult bovine organs. Using a sandwich ELISA, the level of the rather ubiquitous galectin-1 is mostly increased in adult organs relative to respective fetal stages, except for the case of kidney. This developmental course is seen rather seldom, when the amounts of lectin-reactive glycoproteins or glycolipids are quantitated in solid-phase assays after tissue homogenization. Western blotting, combined with probing by labeled galectin-1, discloses primarily quantitative changes in the reactivity of individual glycoproteins. Performing the same assays on extract aliquots with a plant agglutinin, namely the galactoside-binding mistletoe lectin, whose fine specificity is different from galectin-1, its reduced extent of binding in solid-phase assays and the disparate profile of lectin-reactive glycoproteins reveal a non-uniform developmental alteration within the group of structural variants of beta-galactosides. Although sample preparation can affect ligand preservation and/or presentation and thus restricts the comparability of biochemical and histochemical results, especially for soluble reactants, the histochemical studies on frozen and paraffin-embedded sections of bovine heart, kidney and liver demonstrate that the localization of the galectin and of lectin-reactive epitopes can show a similar distribution, as seen in liver and heart, with organ-typical quantitative changes of a rather similar staining profile (heart, kidney) or notable changes in the spatial distribution (liver) in the course of development. This report emphasizes the potential value of combined monitoring of the lectin and its potential in vivo ligands to contribute to eventually unravel organ-related function(s) of a tissue lectin.
TL;DR: The 32-kDa galectin isolated from the nematode Caenorhabditis elegans was the first “tandem repeat-type” galECTin, containing two homologous carbohydrate-binding sites, and was completely determined by the combination of genomic polymerase chain reaction and conventional colony hybridization.
Patent•
09 Oct 1997TL;DR: In this paper, isolated nucleic acid molecules are provided encoding the human Galectin 8, 9, 10 and 10SV proteins, as well as vectors, host cells and recombinant methods for producing the same.
Abstract: The present invention relates to novel galectin 8, 9, 10 and 10SV proteins which are members of the galectin superfamily. In particular, isolated nucleic acid molecules are provided encoding the human galectin 8, 9, 10 and 10SV proteins. Galectin 8, 9, 10 and 10SV polypeptides are also provided as are vectors, host cells and recombinant methods for producing the same. The invention further relates to screening methods for identifying agonists and antagonists of galectin 8, 9, 10 or 10SV activity. Also provided are diagnostic and therapeutic methods.
Journal Article•
TL;DR: The results indicate that endogenous lectins may be involved in the regulation of neutrophil and lymphocyte functions by elicitation of selective biosignaling reactions.
Abstract: In contrast to plant agglutinins, biological activities of animal/human lectins are not well defined yet Testing a panel of seven mammalian carbohydrate-binding proteins we have found that the dimeric lectin from chicken liver (CL-16) was a stimulator of H2O2 release from human neutrophils as well as effector for induction of cytosolic Ca2+ and pH increase in rat thymocytes Activity of this lectin was comparable to potent galactoside-specific plant lectins such as Viscum album L agglutinin The activities of the tested plant lectins depended significantly on their nominal carbohydrate specificity as well as on the source The results indicate that endogenous lectins may be involved in the regulation of neutrophil and lymphocyte functions by elicitation of selective biosignaling reactions
TL;DR: It is confirmed that 36kDa will be joining the CRD programme in 2017.
Abstract: 現在、哺乳類には10種類のガレクチンがあることが示されている。この章ではそのうち5つについて、各ガレクチンの発見の経緯と特徴について述べようと思う。ガレクチン-2はガレクチン-1と同様、14kDaのサブユニットが2量体構造をした分子で、腸上皮細胞に発現している。ガレクチン-5は15kDaの単量体ガレクチンで、赤血球に発現している。最近発見されたガレクチン-9は多くの組織で発現している36kDaのタンパク質で、2つの糖認識ドメイン (CRD) からなり、このうちC-末端側のCRDがガレクチン-5と非常に高い類似性を示す。ガレクチン-4と-6は互いにきわめて似た分子で、それぞれ36kDaと34kDaの分子量を持ち、やはりともに2つのCRDからなり、両者とも消化管の上皮細胞で発現している。
TL;DR: It is demonstrated for the first time that galectin-3 decreases thymidine incorporation in breast cancer cells, and the mechanism underlying this property and its importance during breast cancer development remain to be elucidated.
Abstract: Galectin-3 is a 30-kDa galactose-binding protein member of the galectin family. Galectin-3 is involved in multiple intracellular and extracellular biological functions, e.g. interactions with laminin and with nucleic acids. This latter property is consistent with the presence of 3. serum-response factor-like domain at the amino-terminal part of the protein. Galectin-3 expression is upregulated during serum-mediated induction of proliferation. In order to examine the role of galectin-3 in breast cancer cell proliferation, we examined in this study the influence of antisense galectin-3 complementary DNA stable transfection on the in vitro thymidine incorporation of human breast cancer MDA-MB435 cells. Two stable transfectants, clones 5.24 and 5.29, were selected based both on the presence of a complete CMV promoter-antisense galectin-3 cDNA cassette as assayed by polymerase chain reaction, and on efficient down-regulation of galectin-3 protein expression as determined by Western blotting. Thymidine incorporation experiments showed that both clones were characterized by significantly decreased values of DNA incorporation compared to wild-type transfectants (55 to 68%, and 71 to 82% of the control clone values). Our data demonstrate for the first time that galectin-3 decreases thymidine incorporation in breast cancer cells. The mechanism underlying this property of galectin-3 and its importance during breast cancer development remain to be elucidated.
TL;DR: The results indicate that Rana oocytes contain abundant galectin in their yolk platelets in contrast to Xenopus laevis oocytes, which have been found not to contain galectins but other classes of lectins in their Yolk Platelets and cortical granules.
Abstract: Galectins are a family of lectins that recognize beta-D-galactosides independently of calcium ions, and are widely distributed in animals. To characterize a galectin previously purified from oocytes of Rana catesbeiana (American bullfrog), we studied its distribution and localization in several tissues from this frog. Hemagglutination assay and western blotting showed that this lectin is present in many tissues including the liver, skin, kidney, skeletal muscle, and sciatic nerve, but is particularly concentrated in the ovary. Light microscopic immunohistochemistry showed that this lectin is localized in such places as cell-cell junctions, basement membranes, extracellular matrix, or secretory substances in several organs, indicating that this galectin is mainly distributed extracellularly. However, in the ovary, light microscopy showed that this lectin is present in or associated with the yolk platelet. Electron microscopy further revealed that it is localized in the periphery of the yolk platelet (the yolk plasm), but not in the cortical granule. These results indicate that Rana oocytes contain abundant galectin in their yolk platelets in contrast to Xenopus laevis oocytes, which have been found not to contain galectins but other classes of lectins in their yolk platelets and cortical granules.
TL;DR: X-ray data of bovine heart galectin-1 is applied as a template for homology modelling of a number of galectins from mammalian and avian tissues and shows comparable alterations when they are recorded by CIDNP-technique in the absence and in the presence of their specific carbohydrate ligands.
Abstract: Galectins (Galactose binding lectins) from bacteria, plants and animals have been shown to possess tyrosine or tryptophan residues that form hydrophobic contacts with their ligands in the binding sites. At the present time, the X-ray structures of only two galectins from human and bovine tissues are known. In the present study we applied X-ray data of bovine heart galectin-1 as a template for homology modelling of a number of galectins from mammalian and avian tissues. The conservation of one tryptophan and at least one histidine in binding pocket can be observed from the comparison of the model structures. We also show that it is possible to obtain information of the architecture of the binding pocket of several galectins in solution using CIDNP (Chemically Induced Dynamic Nuclear Polarisation) techniques. The CIDNP approach offers a possibility to analyse these lectins in solution thereby providing supplementary information to the available X-ray data. All studied galectins show comparable alterations when they are r ecorded by CIDNPtechnique in the absence and in the presence of their specific carbohydrate ligands.
01 Jan 1997
TL;DR: Although the number of reported animal lectins continues to increase, a recent classification indicates that most fall into one of five major groups: the Ca2+-dependent (C-type) lectins, the galectins (galactose binding proteins), the mannose-6-phosphate-binding (P- type) Lectins, and the immunoglobolin-like (I-types), related in sequence to the leguminous plant lectins.
Abstract: Lectins constitute a structurally diverse class of proteins or glycoproteins which are characterized by their ability to bind carbohydrates with considerable specificity [1–3]. They are found in various organisms, ranging from viruses, bacteria and plants to humans. There is increasing evidence that carbohydrate-lectin interactions have a fundamental role in cell adhesion processes [4,5], cell proliferation [6], organogenesis and human pathology. Lectins merely bind but do not process carbohydrates. In contrast to, for example, antibodies, which can also bind carbohydrates, lectins are produced constitutively and not as a result of an external stimulus [7,8]. Lectins have been grouped into classes of discrete families based on homologies in their primary structures [9]. Although the number of reported animal lectins continues to increase, a recent classification [9] indicates that most fall into one of five major groups: the Ca2+-dependent (C-type) lectins, the galectins (galactose binding proteins), the mannose-6-phosphate-binding (P-type) lectins, and the immunoglobolin-like (I-type) lectins including sialoadhesins and L-type lectins, related in sequence to the leguminous plant lectins. While the overall architecture of the lectins widely varies, carbohydrate-binding activity can often be assigned to one part of the structure, called a carbohydrate recognition domain (CRD). C-type CRDs are present in a diverse array of protein structures which have been found in serum, extracellular matrix and membranes of animals.