Lectins: A Bridge Between Glycobiology Research and Diagnostic Biomarkers
Lectins: A Bridge Between Glycobiology Research and Diagnostic Biomarkers
In both eukaryotes and prokaryotes, a large proportion of proteins and lipids carry complex oligosaccharide chains in the form of N- or O-linked glycosylation. These glycans participate in key processes such as cell adhesion, signal transduction, immune regulation, and pathogen invasion. Lectins are a class of non-immune proteins capable of specifically recognizing carbohydrate structures. Through their carbohydrate-recognition domains, they bind to particular monosaccharides or oligosaccharides and effectively “decode” glycan patterns on the cell surface or in soluble environments. In experimental systems, well-characterized lectins with defined specificities and their derivative reagents have become essential tools for studying structure–function relationships of glycosylation and for conducting glycomics analyses.
I. What Are Lectins?
Lectins are non-immune proteins or glycoproteins that can reversibly and specifically bind to sugars or glycoproteins. Rather than relying on antigen–antibody recognition, they bind oligosaccharides via their intrinsic carbohydrate-recognition domains (CRDs), thereby recognizing glycan patterns on cell surfaces or in solution.Lectins are widely distributed in plants, animals, fungi, bacteria, and viruses, and in their natural context they participate in various biological processes, including pathogen adhesion, host defense, cell adhesion, and signal transduction. In the laboratory, lectins serve as important molecular tools for studying glycobiology and the structures of glycoproteins.
II. Structural Features and Mechanism of Glycan Recognition
Most lectins consist of one or more carbohydrate-recognition domains (CRDs), which may be repeated or differ in specificity within the same molecule. CRDs bind specific monosaccharide or oligosaccharide residues through hydrogen bonding, hydrophobic interactions, van der Waals forces, and coordination with metal ions such as Ca²⁺, Mn²⁺, and Mg²⁺. For example, some legume lectins from plants require Ca²⁺/Mn²⁺ to maintain glycan-binding activity.Lectin recognition can display a “monosaccharide preference” (e.g., for Man, Gal, GlcNAc), and can also show selectivity toward higher-order structures such as branched N-glycans, terminal motifs of O-glycans, or sialylated glycans. This “glycan fingerprint” style of binding underpins their applications in glycomics.
III. Major Types and Common Representatives
Based on origin, lectins can be broadly categorized into plant lectins, animal lectins, and microbial/fungal lectins. In experimental applications, plant lectins with well-defined origin and stable specificity are the most commonly used.
1. Plant Lectins
Typical examples include concanavalin A (ConA), which preferentially binds α-D-mannose/glucose residues; peanut agglutinin (PNA), which recognizes terminal Galβ1-3GalNAc structures; wheat germ agglutinin (WGA), which binds N-acetylglucosamine and sialylated structures; and soybean agglutinin (SBA), which has high affinity for GalNAc. In terms of product forms, these lectins are commonly available as unlabeled powders, affinity chromatography media, magnetic beads, as well as various fluorescently labeled forms (such as FITC-ConA, TRITC-PNA, Alexa Fluor-labeled WGA) and biotin-labeled forms, and can be flexibly used in flow cytometry, fluorescence microscopy, ELISA and affinity purification.
2. Animal, Microbial, and Fungal Lectins
A typical example from animals is the C-type lectin family, such as certain hepatic receptors and DC-SIGN on dendritic cells. These proteins are often studied as receptors in receptor–ligand interaction research.Microbial and fungal lectins are frequently associated with host adhesion and invasion, such as sugar-binding proteins on bacterial flagella or pili, and glycan-binding subunits in fungal toxins. Experimentally, they can be obtained through purification or recombinant expression and used as probes for functional studies.
IV. Typical Applications of Lectins in Biological Research
1. Cell Surface Glycan Analysis and Phenotyping
The composition of cell surface glycans differs significantly between cell types and between different cell states. By staining live or fixed cells with fluorescently labeled lectins, one can analyze the distribution and abundance of glycans on the cell surface using fluorescence microscopy or flow cytometry. Combined with multicolor antibody co-staining, “surface marker–glycan phenotype” information can be acquired simultaneously from the same sample.Lectin microarrays constructed from multiple lectins with distinct specificities can be used to generate glycan fingerprints of cell lines, tissue samples, or serum glycoproteins. This provides tools for tumor classification, stem cell status monitoring, and investigation of disease-associated glycan alterations.
2.Lectin affinity chromatography and glycoprotein fractionation
By coupling lectins to polysaccharide matrices or magnetic bead surfaces, lectin affinity media can be prepared to build affinity chromatography systems that are specific for particular glycan types. For example, ConA affinity media can be used to enrich high-mannose and hybrid-type N-glycoproteins; WGA-based media can be used to capture glycoproteins containing GlcNAc or sialylated structures; PNA-based media can be used to enrich O-glycoproteins with desialylated terminal structures. Through gradient elution or by adding specific competing sugars (such as methyl-α-D-mannoside, N-acetylglucosamine, etc.), glycoproteins can be fractionated and partially separated, providing highly selective pretreatment for subsequent mass spectrometry identification, functional studies or preparative purification.
3.Histology and auxiliary pathological diagnosis
By applying HRP-labeled or fluorescently labeled lectins on tissue sections or frozen sections, the glycan patterns of different cell populations such as vascular endothelial cells, tumor cells and neurons can be visualized and analyzed. For example, UEA-I is often used to label certain types of vascular endothelium; PNA can be used to detect incompletely sialylated terminal O-glycans in tumor tissues; WGA can be used to show GlcNAc-rich basement membranes or nerve fibers. Combined with routine H&E staining, immunohistochemistry or immunofluorescence, lectin staining can provide additional information on tumor malignancy, tissue differentiation status and the microenvironment of lesion areas.
4.Receptor–ligand interactions and endocytosis studies
Many lectins themselves are cell receptors or components of receptor complexes. In in vitro experiments, specific lectins conjugated to fluorescent probes or nanoparticles can be used to study how cells recognize and internalize ligands with specific glycan patterns; conversely, soluble glycans or glycoconjugates can be used to inhibit interactions between endogenous lectins and their ligands in order to dissect related signaling pathways. In such experiments, the combined use of fluorescently labeled lectins, biotin–lectin plus streptavidin–HRP systems, and competing mono- or oligosaccharides allows relatively systematic evaluation of binding specificity and endocytic kinetics.
5.Glycomics and diagnostic biomarker screening
By using a set of lectins with different specificities to construct lectin arrays or perform lectin blotting, overall glycan profiles of glycoproteins in complex samples can be rapidly obtained, which is particularly suitable for comparing glycan differences in serum, plasma or cellular secretomes between healthy and disease states. In combination with high-resolution mass spectrometry and quantitative proteomics techniques, “lectin-enriched signals” can be correlated with specific protein targets to screen potential glycosylation-related biomarkers. During method development, it is often necessary to use high-purity lectins, standard glycoproteins and corresponding chromogenic or fluorescent substrates to ensure the reliability of glycan recognition and signal readout.
V. Notes for use
1.Ions and buffer conditions
The glycan-binding activity of many lectins depends on divalent metal ions, most commonly Ca²⁺, Mn²⁺ and Mg²⁺. Therefore, appropriate amounts of these metal salts need to be added to the buffer system, and chelating agents such as EDTA should be avoided. In most cases, the buffer pH is chosen in the range 7.0–7.4 to balance protein stability and cell condition.
2.Specificity verification and sugar inhibition experiments
Although lectins have well-defined sugar preferences, some degree of nonspecific binding may still occur in complex biological samples. When designing experiments, it is recommended to perform competitive inhibition experiments using the corresponding monosaccharides or oligosaccharides (such as D-mannose, D-galactose, GlcNAc, lactose, lactosamine, etc.): high concentrations of competing sugars are added during preincubation or elution; if the signal decreases significantly, this can to some extent demonstrate that the interaction is sugar-dependent and thus enhance the reliability of data interpretation.
3.Label formats and signal detection
The same lectin can be provided in multiple labeled forms, such as FITC, TRITC, Cy dyes, Alexa Fluor dyes, HRP, and biotin–lectin used in combination with streptavidin–HRP. When choosing a labeling format, one needs to consider in combination the excitation sources available on the instrument, the spectral bands already occupied by other dyes or antibodies, and whether quantitative analysis is required. For flow cytometry and high-content imaging, fluorescent lectins with high brightness and good photostability are often selected; in lectin blotting, ELISA and affinity capture applications, HRP-labeled or biotin-labeled lectins are usually preferred.
4.Cytotoxicity and cross-reactivity
Some lectins, at relatively high concentrations, can induce cell aggregation or even trigger cell death signaling. Therefore, when performing live-cell staining or functional experiments, the working concentration should be controlled, and time-course and dose–response pre-experiments should be carried out to evaluate cell status. For experimental schemes using multiple lectins in combination, attention should also be paid to possible interactions or competition between different lectins; if necessary, stepwise incubation or adjustment of incubation order can be adopted.
5.Storage and preparation
Lectins are protein reagents and generally need to be stored at low temperature and protected from light. According to the instructions, appropriate amounts of sugars or stabilizers can be added to improve stability. Working solutions are recommended to be prepared freshly before use; prolonged standing at room temperature may lead to loss of activity or self-aggregation, affecting experimental reproducibility.
VI. Related products
1. Concanavalin A (Con A)
Concanavalin A is a plant lectin purified from jack bean (Canavalia ensiformis) that specifically binds α-mannose / α-glucose residues. It is widely used for glycoprotein purification, cell-surface glycan probing, and as a T-cell mitogen.
Catalog No. | Product Name | Grade and Purity |
Concanavalin A, AF488 conjugate | Suitable for immunofluorescence (IF), BioReagent, 1.0 mg/mL | |
Concanavalin A, AF594 conjugate | Suitable for immunofluorescence (IF), BioReagent, 1.0 mg/mL | |
Concanavalin A, AF647 conjugate | Suitable for immunofluorescence (IF), BioReagent, 1.0 mg/mL | |
Concanavalin A, FITC conjugate | Suitable for immunofluorescence (IF), BioReagent, 1.0 mg/mL | |
Concanavalin A, Biotin conjugate | BioReagent, Suitable for immunofluorescence (IF), 1.0 mg/mL | |
Concanavalin A lectin (Con A) | ≥90% |
2. Wheat Germ Agglutinin (WGA) & Triticum vulgaris lectin
Wheat germ agglutinin (WGA) is a lectin from wheat (Triticum spp.) that binds N-acetyl-D-glucosamine (GlcNAc) and sialic acid residues; succinylated WGA is more selective for β-GlcNAc. WGA and related wheat lectins are classic tools for labeling cell surfaces and glycoconjugates.
2.1 Fluorescent / biotinylated WGA
Catalog No. | Product Name | Grade and Purity |
Wheat Germ Agglutinin (WGA), AF488 conjugate | Suitable for immunofluorescence (IF), BioReagent, 1.0 mg/mL | |
Wheat Germ Agglutinin (WGA), TRITC conjugate | BioReagent,Suitable for immunofluorescence (IF),1.0 mg/mL | |
Wheat Germ Agglutinin (WGA), Biotin conjugate | Suitable for immunofluorescence (IF),BioReagent,1.0 mg/mL | |
Wheat Germ Agglutinin | -- | |
Wheat Germ Agglutinin (Fluorescein) | -- | |
Succinylated Wheat Germ Agglutinin (Fluorescein) | -- |
2.2 Triticum vulgaris lectin (wheat lectin) powders & conjugates
Catalog No. | Product Name | Grade and Purity |
Lectin from Triticum vulgaris (wheat) | FITC conjugate, lyophilized powder | |
Lectin from Triticum vulgaris (wheat) | agarose conjugate, saline suspension | |
Lectin from Triticum vulgaris (wheat) | biotin conjugate, lyophilized powder | |
Lectin from Triticum vulgaris (wheat) | peroxidase conjugate, lyophilized powder | |
Lectin from Triticum vulgaris (wheat) | BioReagent, for cell culture, lyophilized powder | |
Lectin from Triticum vulgaris (wheat) | lyophilized powder | |
Lectin from Triticum vulgaris (wheat) | agarose conjugate, saline suspension |
2.3 Wheat germ (hardseed bean) and WGA powders
Catalog No. | Product Name | Grade and Purity |
Lectin from Dolichos biflorus (horse gram) | biotin conjugate, buffered aqueous solution | |
Lectin from Dolichos biflorus (horse gram) | lyophilized powder | |
Lectin from Triticum vulgaris | BioReagent, Native, ≥55% (GE), Protein content ≥85% | |
Triticum vulgaris lectin (WGA) | -- |
3.Soybean agglutinin (SBA)
SBA is derived from soybean Glycine max and preferentially binds terminal GalNAc and galactose residues. It is commonly used for stem cell sorting, glycoprotein glycan profiling, and studies of soybean anti-nutritional factors.
Catalog No. | Product Name | Grade and Purity |
Soybean Agglutinin | -- | |
Glycine Max lectin (SBA) | -- | |
Soybean Agglutinin (Fluorescein) | -- | |
Soybean Agglutinin (Agarose) | -- | |
Soybean Agglutinin (Biotinylated) | -- | |
Lectin from Glycine max (soybean) | lyophilized powder, salt, essentially free |
4.Phaseolus/phytohemagglutinin family (PHA-L/PHA-E/PHA- M/PHA-P)
PHA is the major lectin in the seeds of Phaseolus vulgaris (red kidney bean). It is a tetrameric glycoprotein composed of L subunits (leucoagglutinin) and E subunits (erythroagglutinin); PHA-M/P are mixtures. PHA-L preferentially agglutinates leukocytes and PHA-E preferentially agglutinates erythrocytes. They are commonly used as lymphocyte mitogens, for T-cell activation, and as axonal tracers.
Catalog No. | Product Name | Grade and Purity |
Phaseolus vulgaris lectin E (PHA-E) | -- | |
Lectin from Phaseolus vulgaris (red kidney bean) | BioReagent, for cell culture, Leucoagglutinin PHA-L, lyophilized powder | |
Lectin from Phaseolus vulgaris (red kidney bean) | BioReagent, for cell culture, Phytohemagglutinin PHA-P, lyophilized powder (contains ~50% buffer salts as sodium phosphate and NaCl) | |
Lectin from Phaseolus vulgaris (red kidney bean) | BioReagent, Phytohemagglutinin PHA-P, purified by affinity chromatography, lyophilized powder | |
Lectin from Phaseolus vulgaris (red kidney bean) | BioReagent, for cell culture, Phytohemagglutinin PHA-M, lyophilized powder | |
PHA-M (red kidney bean) | BioReagent, 50%~70%, Phytohemagglutinin PHA-M, lyophilized powder | |
PHA-P (red kidney bean) | BioReagent, ≥70%, Phytohemagglutinin PHA-P, lyophilized powder | |
Lectin from Phaseolus vulgaris (red kidney bean)（PHA-P） | -- | |
PHA-L (red kidney bean) | BioReagent, Leucoagglutinin PHA-L, lyophilized powder | |
PHA-E (red kidney bean) | BioReagent, ≥80%, Erythroagglutinin PHA-E | |
Phaseolus vulgaris lectin M (PHA-M) crude | -- | |
Phaseolus vulgaris lectin L (PHA-L) | -- | |
Lens Culinaris Agglutinin (Fluorescein) | -- | |
Lens Culinaris Agglutinin (Biotinylated) | -- | |
Phaseolus vulgaris leucoagglutinin | -- | |
Phaseolus Vulgaris Leucoagglutinin (Fluorescein) | -- | |
Phaseolus Vulgaris Leucoagglutinin (Biotinylated) | -- | |
Phaseolus Vulgaris Erythroagglutinin | -- |
5.Peanut agglutinin (PNA)
PNA is derived from peanut Arachis hypogaea and specifically recognizes the Thomsen–Friedenreich antigen (Galβ1-3GalNAc). It is commonly used for tumor tissue grading, lymphocyte subset discrimination, and stem cell sorting.
Catalog No. | Product Name | Grade and Purity |
Lectin from Arachis hypogaea (peanut) | FITC conjugate | |
Peanut Agglutinin (CY3) | -- | |
Peanut Agglutinin (Rhodamine) | -- | |
Peanut Agglutinin (Fluorescein) | -- | |
Peanut Agglutinin (Agarose) | -- | |
Peanut Agglutinin (Biotinylated) | -- | |
Lectin from Arachis hypogaea (peanut) | peroxidase conjugate, lyophilized powder | |
Lectin from Arachis hypogaea (peanut) | lyophilized powder, Affinity-purified | |
Arachis hypogaea lectin (PNA, Peanut Agglutinin) | -- |
6.Griffonia simplicifolia lectins (GSL I)
These lectins are derived from Griffonia simplicifolia (Ghana bean). Isolectin B4 (GSL I-B4) in particular has affinity for terminal α-Gal residues. It is a classical probe for tracing unmyelinated C-fiber nerves and labeling small-diameter neurons, and is also widely used in studies of glycan structures.
6.1GSL I / II (Griffonia simplicifolia lectin I/II)
Catalog No. | Product Name | Grade and Purity |
Griffonia (Bandeiraea) Simplicifolia Lectin I | -- | |
Griffonia (Bandeiraea) Simplicifolia Lectin II | -- | |
Griffonia (Bandeiraea) Simplicifolia Lectin II (Fluorescein) | -- | |
Griffonia (Bandeiraea) Simplicifolia Lectin I (Rhodamine) | -- | |
Griffonia (Bandeiraea) Simplicifolia Lectin I (Fluorescein) | -- |
6.2Isolectin B4 / BSI-B4 series
Catalog No. | Product Name | Grade and Purity |
Griffonia Simplicifolia Lectin I Isolectin B4 (Fluorescein) | -- | |
Griffonia Simplicifolia Lectin I Isolectin B4 (Biotinylated) | -- | |
Griffonia Simplicifolia Lectin I Isolectin B4 | -- | |
Lectin from Bandeiraea simplicifolia (Griffonia simplicifolia) | Isolectin B4 (BSI-B4), biotin conjugate, lyophilized powder | |
Lectin from Bandeiraea simplicifolia (Griffonia simplicifolia) | Isolectin B4 (BSI-B4), lyophilized powder | |
Lectin from Bandeiraea simplicifolia (Griffonia simplicifolia) | FITC conjugate, lyophilized powder | |
Lectin from Bandeiraea simplicifolia (Griffonia simplicifolia) | Isolectin B4 (BSI-B4), FITC conjugate, lyophilized powder | |
Lectin from Bandeiraea simplicifolia (Griffonia simplicifolia) | Isolectin B4 (BSI-B4), peroxidase conjugate, lyophilized powder | |
Lectin from Bandeiraea simplicifolia (Griffonia simplicifolia) | lyophilized powder |
7.Datura/Dolichos/Erythrina “glycan-probing” lectins
7.1Datura stramonium lectin (DSL)
DSL is derived from Datura stramonium and preferentially recognizes poly-N-acetyllactosamine sequences. It is commonly used for enrichment of complex N-glycans and for glycan structure analysis.
Catalog No. | Product Name | Grade and Purity |
Datura Stramonium Lectin | -- | |
Datura Stramonium Lectin (Fluorescein) | -- | |
Datura Stramonium Lectin (Biotinylated) | -- |
7.2Dolichos biflorus agglutinin (DBA)
Catalog No. | Product Name | Grade and Purity |
Dolichos Biflorus Agglutinin | -- | |
Dolichos Biflorus Agglutinin (Rhodamine) | -- | |
Dolichos Biflorus Agglutinin (Fluorescein) | -- | |
Dolichos Biflorus Agglutinin (Biotinylated) | -- |
7.3Erythrina cristagalli lectin (ECL)
Catalog No. | Product Name | Grade and Purity |
Erythrina Cristagalli Lectin | -- | |
Erythrina Cristagalli Lectin (Fluorescein) | -- | |
Erythrina Cristagalli Lectin (Agarose) | -- | |
Erythrina Cristagalli Lectin (Biotinylated) | -- |
8.Lectins from tomato, potato, snowdrop, daffodil and related plants
8.1Tomato lectin (LEL/TL)
Tomato lectin is derived from Lycopersicon esculentum and is a tetrameric glycoprotein composed of identical subunits; its carbohydrate chains are rich in arabinose and galactose, and it is commonly used as a marker for blood vessels and microglial cells.
Catalog No. | Product Name | Grade and Purity |
Lycopersicon esculentum (Tomato) Lectin | -- | |
Lectin from Lycopersicon esculentum (tomato) | FITC conjugate, buffered aqueous solution | |
Lycopersicon esculentum (Tomato) Lectin (Fluorescein) | -- |
8.2Potato lectin
Catalog No. | Product Name | Grade and Purity |
Solanum Tuberosum (Potato) Lectin | -- | |
Solanum Tuberosum (Potato) Lectin (Biotinylated) | -- |
8.3Snowdrop/daffodil lectins (GNA/NPA)
Snowdrop GNA and the related NPA/NPL family are mannose-specific and are commonly used in studies of insect resistance, antiviral activity and antitumor effects.
Catalog No. | Product Name | Grade and Purity |
Galanthus Nivalis Lectin | -- | |
Galanthus Nivalis Lectin (GNA) | -- | |
Lectin from Galanthus nivalis (snowdrop) | agarose conjugate, saline suspension | |
Galanthus Nivalis Lectin (Fluorescein) | -- | |
Galanthus Nivalis Lectin (Agarose) | -- | |
Narcissus Pseudonarcissus (Daffodil) Lectin | -- | |
Narcissus pseudonarcissus lectin (NPA/NPL) | -- |
9.Gorse/European gorse lectins (Ulex lectins)
Catalog No. | Product Name | Grade and Purity |
Lectin from Ulex europaeus (gorse, furze) | peroxidase conjugate, lyophilized powder | |
Lectin from Ulex europaeus (gorse, furze) | lyophilized powder | |
Lectin from Ulex europaeus (gorse, furze) | FITC conjugate, lyophilized powder | |
Lectin from Ulex europaeus (gorse, furze) | biotin conjugate, lyophilized powder | |
Ulex Europaeus Agglutinin I | -- | |
Ulex Europaeus Agglutinin I (Rhodamine) | -- | |
Ulex Europaeus Agglutinin I (Fluorescein) | -- | |
Ulex Europaeus Agglutinin I (Agarose) | -- | |
Ulex Europaeus Agglutinin I (Biotinylated) | -- |
10.Wisteria lectin
Catalog No. | Product Name | Grade and Purity |
Lectin from Wisteria floribunda | lyophilized powder | |
Lectin from Wisteria floribunda | buffered aqueous solution, biotin conjugate | |
Wisteria Floribunda Lectin | -- | |
Wisteria Floribunda Lectin (Fluorescein) | -- | |
Wisteria Floribunda Lectin (Biotinylated) | -- | |
Wisteria Floribunda Lectin (Agarose) | -- | |
Ricinus Communis Agglutinin I (Agarose) | -- |
11.Elder/black elder lectins (Sambucus)
Catalog No. | Product Name | Grade and Purity |
Sambucus Nigra Lectin (Agarose) | -- | |
Sambucus nigra lectin, Cy5 | -- | |
Sambucus Nigra Lectin | -- | |
Sambucus Nigra Lectin (CY3) | -- | |
Sambucus Nigra Lectin (Fluorescein) | -- | |
Sambucus Nigra Lectin (Biotinylated) | -- |
Lectin-based reagents provide highly selective approaches for elucidating glycan structures, studying glycoprotein function, and screening glycosylation-related biomarkers. By rationally combining lectins with different specificities and using them in various formats such as fluorescent conjugates, biotin/enzyme conjugates, affinity media, and magnetic beads, a complete technical workflow can be established for cell surface glycan analysis, glycoprotein enrichment, tissue staining, and glycomics-based screening. With the continued development of high-resolution mass spectrometry, high-content imaging, and single-cell multi-omics technologies, the application scope of lectin tool systems in glycobiology and glycosylation-related disease research will keep expanding.