Differences in the mannose oligomer specificities of the closely related lectins from Galanthus nivalis and Zea mays strongly determine their eventual anti-HIV activity

Background

In a recent report, the carbohydrate-binding specificities of the plant lectins Galanthus nivalis (GNA) and the closely related lectin from Zea mays (GNA_maize) were determined by glycan array analysis and indicated that GNA_maize recognizes complex-type N-glycans whereas GNA has specificity towards high-mannose-type glycans. Both lectins are tetrameric proteins sharing 64% sequence similarity.

Results

GNA_maize appeared to be ~20- to 100-fold less inhibitory than GNA against HIV infection, syncytia formation between persistently HIV-1-infected HuT-78 cells and uninfected CD4⁺ T-lymphocyte SupT1 cells, HIV-1 capture by DC-SIGN and subsequent transmission of DC-SIGN-captured virions to uninfected CD4⁺ T-lymphocyte cells. In contrast to GNA, which preferentially selects for virus strains with deleted high-mannose-type glycans on gp120, prolonged exposure of HIV-1 to dose-escalating concentrations of GNA_maize selected for mutant virus strains in which one complex-type glycan of gp120 was deleted. Surface Plasmon Resonance (SPR) analysis revealed that GNA and GNA_maize interact with HIV III_B gp120 with affinity constants (K_D) of 0.33 nM and 34 nM, respectively. Whereas immobilized GNA specifically binds mannose oligomers, GNA_maize selectively binds complex-type GlcNAcβ1,2Man oligomers. Also, epitope mapping experiments revealed that GNA and the mannose-specific mAb 2G12 can independently bind from GNA_maize to gp120, whereas GNA_maize cannot efficiently bind to gp120 that contained prebound PHA-E (GlcNAcβ1,2man specific) or SNA (NeuAcα2,6X specific).

Conclusion

The markedly reduced anti-HIV activity of GNA_maize compared to GNA can be explained by the profound shift in glycan recognition and the disappearance of carbohydrate-binding sites in GNA_maize that have high affinity for mannose oligomers. These findings underscore the need for mannose oligomer recognition of therapeutics to be endowed with anti-HIV activity and that mannose, but not complex-type glycan binding of chemotherapeutics to gp120, may result in a pronounced neutralizing activity against the virus.     

Electron cytochemical study of carbohydrate components in cultured nerve and glial cells of the snail Helix pomatia

• 1.1. A variety of colloidal gold-labelled lectins with different sugar specificities to determine whether different nerve and glial cells of the snail Helix pomatia cultured in vitro, can be distinguished by the carbohydrates that they express was screened. The analysis of lectin binding has shown substantial differences in the carbohydrate pattern between nerve and glial cells and between the soma of monoaminergic and peptidergic neurons.
• 2.2. The surface of monoaminergic and peptidergic neurons contains N-acetylglucosamine and N-acetyllactosamine determinants, and does not exhibit neuraminic acid and complex branched N-glycosyl chains. Moreover, N-acetylgalactosamine can be detected on peptidergic neuron membranes only.
• 3.3. N-Acetylglucosamine residues are not present on the surface of the glial cells, and the density of the N-acetyllactosamine and/or terminal β-galactose residues is much higher here than on the surface of the nerve cells.
• 4.4. These results suggest that nerve cells in the snail brain can be distinguished from glial cells by the presence of a cell-surface glycoconjugate containing terminal N-acetyl-d-glucosamine residues, whereas peptidergic neurons can be distinguished from monoaminergic neurons by the presence of a surface glycoconjugate containing terminal α-linked N-acetyl-d-galactosamine residues.

     

Histochemical study of Hurler's disease by the use of peroxidase-labelled lectins

Summary Peroxidase-labelled lectins specific for various carbohydrate residues were used as histochemical reagents in the investigation of Hurler's syndrome. Peanut lectin was used to detect terminald-galactose, wheatgerm lectin forN-acetyl-d-glucosamine, soybean lectin forN-acetyl-d-galactosamine,Tetragonolobus lotus lectin for -l-fucose andBandeiraea S. lectin for -d-galactose. It was found that Kupffer cells in the liver and splenic reticulo-endothelial cells contain acid mucopolysaccharides which bind lectins in paraffin sections after appropriate fixation. The pattern of lectin binding suggests that such cells contain significant amounts ofd-galactose,l-fucose,N-acetyl-d-galactosamine andN-acetyl-d-glucosamine. It is likely that the last named carbohydrate is present as a polymer. Neurones contain a different carbohydrate, rich in galactose and fucose but poor inN-acetyl-d-glucosamine. This compound is resistant to lipid extraction. Hepatocytes, as a rule, do not react with lectins, most likely because of loss of the more soluble mucopolysaccharides during fixation. The results are consistent with the biochemical data of Hurler's syndrome and indicate that lectins can be a useful tool for the investigation of the cytochemistry of storage disorders.     

Interactions of endogenous lectin from theHelix pomatia reproductive system (HPA) with the surface of CNS neurons of the snail

The surface of unidentified cultured neurons and electrophysiologically identified units RPa1, RPa2, and LPa3 of the snailHelix pomatia was studied using a colloidal gold-labelled endogenous gonad lectin of this molluse (Helix pomatia agglutinin -HPA), which is specific to -anomer N-acetyl-D-galactosamine, and some other lectins. It was found that only two populations of cultured neurons with a specific ultrastructure typical of peptidergic cells and differing from the ultrastructure of other peptidergic and non-peptidergic neurons possessHPA receptors. These neurons average about 1% of cultured nerve cells. Using a variety of plant lectins withHPA-like specificity (LBA, VVA, SBA) showed that the surface of many peptidergic neurons contains -anomer-like structures, yet it does not bindHPA. These data were supported in the experiments on identified snall neurons with the use ofSBA. The results suggest a putative role of endogenous lectins in regulation of activity of neurons participating in processes of secretion in the gonads.Neirofiziologiya/Neurophysiology, Vol. 28, No. 1, pp. 17–29, January–February, 1996.     

A comparison of the carbohydrate binding properties of twoDolichos biflorus lectins

The carbohydrate binding properties of theDolichos biflorus seed lectin and DB58, a vegetative tissue lectin from this plant, were compared using two types of solid phase assays. Both lectins bind to hog blood group A + H substance covalently coupled to Sepharose 4B and this binding can be inhibited with free blood group A + H substance. However, the binding of the seed lectin is inhibited byD-GalNAc whereas DB58 binding was not inhbited by any monosaccharide tested, thus suggesting that its carbohydrate combining site may be more extensive than that of the seed lectin. The activities of these two lectins also differ from one another in ability to recognize blood group A + H substance adsorbed on to plastic and in the effects of salt and urea on their carbohydrate binding activities. Neither lectin showed glycosidase activity with p-nitrophenyl -D-GalNAc or p-nitrophenyl -D-GalNAc.     

Cultivar-Specific Carbohydrate-Binding Properties of Lectins from Broad-Bean Seeds

Lectins were isolated and purified from three broad bean (Vicia faba L.) cultivars differing in the effectiveness of their symbiosis with root nodule bacteria (Rhizobium leguminosarum bv. viciae). From seeds of symbiotically effective cvs. Aushra and Daiva, we isolated only one lectin from each cultivar, whereas two lectins, Yu-1 and Yu-2, were isolated from seeds of symbiotically ineffective cv. Yugeva. Lectins from cvs. Aushra and Daiva were more active than lectins from cv. Yugeva and exhibited similar carbohydrate specificity. Methyl--D-mannopyranoside and trehalose were the most potent inhibitors of their hemagglutination activity. Lectin Yu-1 resembled them in its carbohydrate-binding properties. However, D-mannose, trehalose, and melecitose were its most effective inhibitors. Lectin Yu-2 differed substantially from these lectins. It exhibited an affinity for D-glucuronic acid, D-glucosamine, and 2-deoxy-D-glucose. In addition, it could interact with carbohydrates of the galactose family (2-deoxy-D-galactose, D-galactosamine, and lactose) and also with D-xylose and 2-deoxy-D-talose. Thus, lectins from cvs. Aushra and Daiva and also Yu-1 can be considered D-mannose/D-glucose-specific lectins, whereas Yu-2 lectin exhibited a combined carbohydrate specificity. The affinity of Yu-1 and Yu-2 lectins for their natural receptors, exopolysaccharides and lipopolysaccharides of broad-bean nodule bacteria, was twice as low as that of lectins from cvs. Aushra and Daiva. We believe that properties of seed lectins are an important cultivar-specific trait that determines host-plant (broad beans) specificity during the establishment of legume–rhizobia symbiosis.     

Glycosylation patterns of membrane proteins of the jellyfish Cyanea capillata

Integral and membrane-associated proteins extracted from neuron-enriched perirhopalial tissue of the jellyfish Cyanea capillata were probed with a panel of lectins that recognize sugar epitopes of varying complexity. Of the 13 lectins tested, only concanavalin A, jacalin lectin and tomato lectin stained distinct bands on Western blots, indicating the presence of repeating -1,6-mannoses, terminal Gal--1,6-GalNAc and repeating -1,4-linked GlcNAc, respectively. In whole-mounted perirhopalial tissue, jacalin lectin stained several cell types, including neurons, muscle, cilia and mucus strands. Tomato lectin stained secretory cells intensely, and neurons in a punctate fashion. Concanavalin A stained cytoplasmic epitopes in both ecto-and endodermal cells, and ectodermal secretory cells and the mucus strands emanating from them. With the exception of tomato lectin's sugar epitope, the other sugar epitopes identified in this study are non-complex. This study suggests that while glycosylation of integral and membrane-associated proteins occurs in Cyanea, the sugars post-translationally linked to these proteins tend to be simple.     

Localization of mannose- and galactose-binding lectins in an effective peanut nodule

Summary Mannose/glucose- and galactose-binding lectins (ML and GL respectively, were located by immunogold labelling in tissues of a peanut (Arachis hypogaea) nodule induced by an effectiveBradyrhizobium sp. strain. Light and electron microscopic examination of silver-enhanced semithin and ultrathin sections, respectively, revealed that both lectins were widely distributed throughout the cortex and bacteroidal zones although ML was more abundant. The lectins were predominantly in the vacuoles of cortical cells but GL was absent from, or at low concentration in, a two-cell-thick layer of cortical cells surrounding the bacteroidal region. Only ML was detected in cells of the vascular bundle endodermis and in central vascular bundle cells; neither lectin was found in pericycle cells. Bacteroidal cells contained abundant ML in the nuclei and cytoplasm surrounding bacteroids while GL was mainly located in the central vacuoles of these cells. Neither lectin was associated with bacteroid surfaces, peribacteroid membranes, plant cell walls or cell organelles and membranes. The above observations indicate that the nodule lectins are not symbiotic cell recognition determinants and suggest that they have protein storage functions.Abbreviations BSA bovine serum albumin - GL galactose-binding lectin - ML mannose-binding lectin - PBS phosphate-buffered saline - PBST phosphate-buffered saline plus Tween     

Lectinhistochemical demonstration of galactose- and N-acetyl-d-galactosamine residues in cells of the rat anterior pituitary

Summary Lectins are a useful tool for identification of differently glycosylated hypophyseal hormones, prohormones and glycoconjugates without hormone function. -d-galactose and -N-acetyl-d-galactosamine (GalNAc) containing glycoconjugates were identified by light microscopy with biotinylated lectins in immunocytochemically localized cells of the anterior pituitary of the rat. Galactose, histochemically detectable by the peanut lectin (PNA), was found at penultimate position of the carbohydrate chain after removal of sialic acid. Galactose containing cells correspond to gonadotrophs and thyrotrophs located mainly in medioanterior regions of the pituitary. The lectins from the soybean (SBA) and horse gram (DBA) both specific for GalNAc residues, are bound to round and also polygonal cells corresponding again to gonadotrophs and thyrotrophs.     

Gold-conjugated arabinogalactan-protein and other lectins as ultrastructural probes for the wheat/stem rust complex

Summary Arabinogalactan-protein (AGP, -lectin) was isolated from leek seeds, tested for specificity, conjugated with gold colloids, and used as a cytochemical probe to detect -linked bound sugars in ultrathin sections of wheat leaves infected with a compatible race of stem rust fungus. Similar sections were probed with other gold-labeled lectins to detect specific sugars. AGP-gold detected -glycosyl in all fungal walls and in the extrahaustorial matrix. Other lectin gold conjugates localized galactose in all fungal walls except in walls of the haustorial body. Limulus polyphemus lectin bound only to the outermost layer of intercellular hyphal walls of the fungus. Binding of these lectins was inhibited by their appropriate haptens and was diminished or abolished in specimens pretreated with protease, indicating that the target substances in the tissue were proteinaceous or that polysaccharides possessing affinity to the lectin probes had been removed by the enzyme from a proteinaceous matrix by passive escape. Bindig of Lotus tetragonolobus lectin was limited to the two outermost fungal wall layers but was not hapten-inhibitable. Limax flavus lectin, specific for sialic acids, had no affinity to any structure in the sections. In the fungus, the most complex structure was the outermost wall layer of intercellular hyphal cells; it had affinity to all lectins tried so far, except to Limax flavus lectin and to wheat germ lectin included in an earlier study. In the host, AGP and the galactose-specific lectins bound to the inner domain of the wall in areas not in contact with the fungus. At host cell penetration sites, affinity to these lectins often extended througout the host wall, confirming that it is modified at these sites. Pre-treatment with protease had no effect on lectin binding to the host wall. After protease treatment, host starch granules retained affinity to galactose-specific lectins, but lost affinity for AGP.This paper is listed as Contribution No. 1330, Agriculture Canada Research Station Winnipeg     

Lectin binding sites on the surfaces of the pneumonocytes in human neonatal lung

Summary The surface coating of the pneumonocytes in human neonatal lung was studied by means of an electron microscope technique. Slices of aldehyde-fixed lung tissue were labelled with a horseradish peroxidase conjugate of one of the following lectins:Dolichos biflorus lectin,Triticum vulgaris lectin,Canavalia ensiformis lectin (concanavalin A),Limulus polyphemus lectin,Lotus tetragonolobus lectin andArachis hypogaea lectin. The tissue slices were then incubated in a diaminobenzidine—hydrogen peroxide medium and then postfixed in an osmium tetroxide solution. It was found that the type I and type II pneumonocytes were strongly labelled with the lectins ofTriticum vulgaris, Canavalia ensiformis, Limulus polyphemus andArachis hypogaea. The type I pneumonocytes were also strongly labelled withDolichos biflorus lectin but the staining of type II cells was relatively weak with this agent. Neither type of epithelial cell was labelled withLotus tetragonolobus lectin conjugate. These results suggest that the surface coating of the pneumonocytes in human neonatal lung contains the following carbohydrate groups:N-acetylgalactosamine,N-acetylglucosamine,-d-mannose,-d-galactose and sialic acid.     

Kinetic sedimentation of Rhizobium-aggregates produced by leguminous lectins

Lectins from Canavalia brasiliensis (CnBr), Cratylia floribunda (CFL), Vatairea macrocarpa (VML) and Phaseolus vulgaris (PHA) aggregate Rhizobiumbacteria. The relationship between specific sedimentation rate, (based on bacterial dry biomass) of bacterial aggregates and lectin concentrations was hyperbolic and showed bacterial surface affinity by lectins. R. tropici (Rt), R. leguminosarum bv. phaseoli (Rlp) and R. etli (Re) surfaces showed predominantly receptors of galactosidic nature. The Rt surfaces showed very high affinities (k _s = ±8.6 × 10^–8 ag lectin protein ml^–1) by Gal-specific lectins (PHA and VML), and very low affinities (k_s=± 4.9 × 10^–6) by Glc-specific lectins (CnBr and CFL). The Rlp surface had intermediate affinities by lectins. The Re surface showed high affinities by PHA (k_s= ±1.26 × 10^–8) and intermediate affinities by VML, CnBr and CFL. The relationship between sedimentation specific (based on lectin weight) and bacterial density was a sigmoid and showed lectin affinity by Rt surfaces. The bacterial sedimentation showed positive cooperative binding of lectins. The V_max induced by Glc-specific lectins was ±20 of that produced by Gal-specific lectins. The PHA affinity (k_s= 1.19 mg dry biomass ml^–1) was larger than VML (k_s = 1.23). The Glc-specific lectin affinities were smaller than those of Gal-specific. The apparent binding site number of lectins (n_app) was: 2.7-PHA; 2.2-VML; 3.2-CFL and 3.2-CnBr. The dissociation constant, k_s, of lectin-binding kinetics decreased with sugar-hapten treatment (10 M). The n_app decreased in PHA and CFL, increasing in VML + sugar-hapten treatment. This study showed that there is a difference in Rhizobium surfaces for lectin binding.     

Primary structure characterization of Bothrops jararacussu snake venom lectin

The complete amino acid sequence of the lectin from Bothrops jararacussu snake venom (BJcuL) is reported. The sequence was determined by Edman degradation and amino acid analysis of the S-carboxymethylated BJcuL derivative (RC-BJcuL) and from its peptides originated from enzymatic digestion. The sequence of amino acid residues showed that this lectin displays the invariant amino acid residues characterized in C-type lectins. Amino acids analysis revealed a high content of acidic amino acids and leucine. These findings suggest that BJcuL, like other snake venom lectins, possesses structural similarities to the carbohydrate recognition domain (CRD) of calcium-dependent animal lectins belonging to the C-type -galactoside binding lectin family.     

Electron-cytochemical study of carbohydrate components of the surface membrane of cultured neurons of the edible snail Helix pomatia

An electron-cytochemical study of the structure and topography of carbohydrate determinants of the surface membrane of CNS neurons of the edible snailHelix pomatia cultured in vitro was carried out by means of a set of colloidal goldlabeled lectins. An analysis of binding of lectins having different specificity to carbohydrate determinants shows the inhomogeneity of the carbohydrate pool of the membrane of the body of nerve cells having a different mediator nature. It was established that monoaminergic and peptidergic neurons equally bind lectins PNA, RCA, and WGA and do not demonstrate binding with PVA and LPA. Here HPA, a product of the albumen gland of the edible snailH. pomatia, marks only the membrane of peptidergic neurons. A conclusion is made about the absence of terminal residues of sialic acid on the membrane of many types of the snail neurons, which may be due to characteristics of its molecular structure. It is suggested also that the differences in the carbohydrate composition of the glycocalyx of different types of cells can serve as the basis for the formation of specific connections between different types of neurons of the developing brain.A. A. Bogomolets Institute of Physiology, Ukrainian Academy of Sciences, Kiev. Translated from Neirofiziologiya, Vol. 24, No. 3, pp. 291–298, May–June, 1992.     

Lectin cytochemistry of cell types in human and canine pituitary

Summary Labeled lectins specific for different sugars were employed to identify different cell types in pituitaries from six human autopsies and seven dogs. To determine the lectins bound by each cell type, fixed-paraffin embedded sections serial to those stained with lectins were immunostained for specific hormones and the serial pairs were examined in a comparison microscope. In human pituitaries corticotrophs stained selectively with lectins having affinity for -l-fucose and the core region of complex type N-glycosyl-proteins. Some corticotrophs also stained for the presence of terminal -galactose. Thyrotrophs stained selectively with a periodate oxidation-borohydride reduction-concanavalin A sequence. Some mammotrophs evidenced content of glycoconjugate with terminal -galactose. Dendritic cells stained selectively for abundant glycogen with the periodate-reduction-concanavalin A sequence and a lectin from Griffonia simplicifolia. Adenohypophyseal cells of dog pituitary differed in showing absence of terminal -galactose in corticotrophs, presence of terminal -galactose in thyrotrophs, presence of glycoconjugate with N-glycosidically bound oligosaccharide in thyrotrophs and gonadotrophs and presence of terminal -galactose with a different lectin affinity in mammotrophs. The main contributions of lectin histochemistry applied to the pituitary include providing an additional histologic method for identification of some cell types, and localizing glycosylated prohormone or other biochemically unrecognized non-hormone glycoconjugates whose function in pituitary cells remains to be explained.This research was supported by NIH Grants AM-10956 and HL-29775 and United Health and Medical Research Foundation of South Carolina, Inc. Grant #79     

Differential recognition of natural and remodeled glycotopes by three Diocleae lectins

The carbohydrate specificities of Dioclea grandiflora lectins DGL-I¹ and DGL-II, and Galactia lindenii lectin II (GLL-II) were explored by use of remodeled glycoproteins as well as by the lectin hemagglutinating activity against erythrocytes from various species with different glycomic profiles. The three lectins exhibited differences in glycan binding specificity but also showed overlapping recognition of some glycotopes (i.e. Tα glycotope for the three lectins; IIβ glycotope for DGL-II and GLL-II lectins); in many cases the interaction with distinct glycotopes was influenced by the structural context, i.e., by the neighbouring sugar residues. Our data complement and expand the existing knowledge about the binding specificity of these three Diocleae lectins, and taken together with results of previous studies, allow us to suggest a functional map of the carbohydrate recognition which illustrate the impact of modification of basic glycotopes enhancing, permiting, or inhibiting their recognition by each lectin.     

Investigating the glycosylation of normal and ovarian cancer haptoglobins using digoxigenin-labelled lectins

Human haptoglobin (Hp), prepared from 10 normal sera and 10 ovarian cancer sera as well as from 11 ovarian cancer ascitic fluids, was characterized with regard to its reactivities with different lectins. Digoxigenin-labelled lectins [peanut agglutinin (PNA),Arachis hypogaea; SNA,Sambucus nigra; MAA,Maackia amurensis; DSA,Datura stramonium; and Con A, concanavalin A] with different carbohydrate specific moieties were used to identify sugar structures in Hp by blotting and by a quantitative assay in multiwell plates [lectin/enzyme-linked immunosorbent assay (ELISA)]. It was found that the lectin blotting was only useful for preliminary investigations, but that the lectin/ELISA gave interesting results that indicated the presence ofN-linked complex chains. Despite the fact that PNA interacted weakly with desialylated Hp in lectin blotting, no other evidence was obtained to suggest the presence ofO-linked glycans. Quantitative differences between normal and cancer Hp were observed for Con A, SNA and MAA, but no difference was found in the reaction with DSA. The binding of cancer Hp to Con A and SNA was twice that of normal Hp. Normal serum and ascitic fluid Hp bound similar amounts of MAA, but three times that observed for cancer serum Hp. Our results suggest that normal and ovarian cancer Hp differ in the content of carbohydrate structures containing sialic acid linked (2–6) or (2–3) to galactose and the type of oligosaccharide branching.     

Lectin binding sites in normal and phenobarbitale/halothane treated rat liver

Summary The content of carbohydrate residues of both normal and phenobarbitale-halothane-hypoxia exposed rat liver has been examined by means of lectin histochemistry. Eight biotinylated lectins specific to galactose, N-acetyl-galactosamine, N-acetyl-glucosamine, fucose and mannose were applied to paraffin sections of rat liver at light microscopic levels. The most distinct binding was observed at the structures of the perisinusoidal functional unit: Kupffer cells are bound by S-WGA, SBA and PNA. Bile canaliculi display binding sites for RCA I and WGA. Cytoplasm of hepatocytes appears lectin-negative, except for PSA. The enhanced reaction of S-WGA, PNA and SBA after the preincubation of the sections with neuraminidase indicates the occurance of sialic acid in Kupffer cells. The phenobarbitale-halothane-hypoxia exposed rat liver shows centrolobular degeneration of hepatocytes with a diminished amount of hepatocytes and Kupffer cells as well. The lectin binding pattern of sinusoidal walls, membranes of hepatocytes and bile canaliculi remains the same compared to that of normal rat liver. This finding suggests that at least the carbohydrate content of membranes in the liver resists severe destruction under phenobarbitale-halothane-hypoxia. It is assumed that there exists a connection between intact carbohydrate residues and the regeneration of liver parenchyma.     

Characterization of diverse hemolymph lectins in the cotton caterpillar Spodoptera littoralis

• 1.1. Hemolymph lectins (agglutinins) of the cotton caterpillar Spodoptera littoralis were analyzed by agglutination, cross-absorption and carbohydrate-hemagglutination inhibition using several vertebrate erythrocytes.
• 2.2. Lectins were found to interact, with all tested erythrocytes, by binding to carbohydrate moieties but showing no definite specificity.
• 3.3. Disulphide bonds were probably absent as 2-ME treatment was ineffective.
• 4.4. By cross-absorption studies, we have proposed that the hemolymph contains multiple lectins.

     

Lectin localization in human nerve by biochemically defined lectin-binding glycoproteins,neoglycoprotein and lectin-specific antibody

Summary Molecular recognition can be mediated by protein (lectin)-carbohydrate interaction, explaining the interest in this topic. Plant lectins and, more recently, chemically glycosylated neoglycoproteins principally allow to map the occurrence of components of this putative recognition system. Labelled endogenous lectins and the lectin-binding ligands can add to the panel of glycohistochemical tools. They may be helpful to derive physicologically valid conclusions in this field for mammalian tissues. Consequently, experiments were prompted to employ the abundant -galactoside-specific lectin of human nerves in affinity chromatography and in histochemistry to purify and to localize its specific glycoprotein ligands. In comparison to the -galactoside-specific plant lectins fromRicinus communis andErythrina cristagalli, notable similarities were especially detectable in the respective profiles of the mammalian and the Erythrina lectin. They appear to account for rather indistinguishable staining patterns in fixed tissue sections. Inhibitory controls within affinity chromatography, within solid-phase assays for each fraction of lectin-binding glycoproteins and within histochemistry as well as the demonstration of crossreactivity of the three fractions of lectin-binding glycoproteins with the biotinylated Erythrina lectin in blotting ascertained the specificity of the lectin-glycoprotein interaction. In addition to monitoring the accessible cellular ligand part by the endogenous lectin as probe, the comparison of immunohistochemical and glycohistochemical detection of the lectin in serial sections proved these methods for receptor analysis to be rather equally effective. The observation that the biotinylated lectin-binding glycoproteins are also appropriate ligands in glycohistochemical analysis warrants emphasis. Overall, the introduction of biotinylated mammalian lectins as well as the lectin-binding glycoproteins will aid to critically evaluate the physiological significance of the glycobiological interplay between endogenous lectins and distinct carbohydrate parts of cellular glycoconjugates.