Zebrafish tissue section. Texas Red-X goat anti–mouse IgG, Alexa Fluor 350 wheat germ agglutinin, SYTOX Green nucleic acid stain.

Lectins are carbohydrate binding proteins that are highly specific to sugar groups attached to other molecules. Lectins, because of their specificity to their target, can serve to identify cell types or cellular components when used in conjunction with various labeling approaches, including histochemistry. Changes in processes of differentiation or in cancerous cell types are often identified by the makeup of their surface glycoproteins, making lectins useful markers in detecting those distinct cellular phenotypes. Fluorescent derivatives, or conjugated lectins, have been used to localize and detect cell-surface or intracellular glycoconjugates, making them versatile primary detection reagents for microscopy or with flow cytometry.

Lectins are available conjugated to a wide variety of fluorescent dyes, including bright, photostable Alexa Fluor dyes, increasing the flexibility in designing multicolor experiments for imaging and flow cytometry. Special conjugation procedures are used to optimize the number of dye molecules bound to the lectins, leaving a bright signal while preserving the binding specificity of the individual lectin. High signal to noise ratio is also maintained by the removal of unconjugated fluorochromes and inactive lectins. Below are two examples of fluorescent lectin labeling in an immunohistochemistry experiment (left) versus an immunocytochemistry experiment (right).

Osteosarcoma cells. Alexa Fluor 488 concanavalin A, Alexa Fluor 594 wheat germ agglutinin and Hoechst 33342 nucleic acid stain. Fixed and permeabilized osteosarcoma cells simultaneously stained with the fluorescent lectins Alexa Fluor 488 concanavalin A (Con A) (Cat. No. C11252) and Alexa Fluor 594 wheat germ agglutinin (WGA) (Cat. No. W11262). Con A selectively binds a-glucopyranosyl residues, whereas WGA selectively binds sialic acid and N-acetylglucosaminyl residues. The nuclei were counterstained with blue-fluorescent Hoechst 33342 nucleic acid stain (Cat. No. H1399, H3570, H21492). The image was acquired using bandpass filter sets appropriate for the Texas Red® dye, fluorescein and DAPI.

Lectins and their properties

LectinSourceCommon AbbreviationUnconjugated Molecular Wt. (kDa)Preferred Sugar SpecificityBlood Group SpecificityMitogenic Activity
Arachis hypogaeaPeanutPNA110T antigen (M, N)ß-gal(1->3)galNAcNo
Canavalia ensiformisCanavalia ensiformis (jack bean)Con A104Non-specific after neuraminidase treatment.α-man, α-glcYes
Canavalia ensiformisCanavalia ensiformis (jack bean)Succinylated Con A56Non-specific after neuraminidase treatment.α-man, α-glcYes
Dolichos biflorusHorse gramDBA111A1α-galNAcNo
Glycine maxSoybeanSBA120A>O>Bα>ßGalNAcYes
Griffonia (Bandeiraea) simplicifolia I Isolectin B4Africa Shrub legumeGSL I - B4, GS-IB4114BαGalNo
Griffonia (Bandeiraea) simplicifolia IIAfrica Shrub legumeGSL II, BSL II, GS II113B>>A1α or ß GalNAcNo
Helix pomatiaEdible snailHPA79AgalNAcNo
Lens culinarisLentilLcH, LCA50Non-specific after neuraminidase treatment.αMan, αGlcYes
Lotus tetragonolobusAsparagus peaLotus107O<A2αFucYes
Lycopersicon esculentumTomatoLEA, LEL, TL71Non-specific after neuraminidase treatment.(glcNAc)3Yes
Phaseolus vulgarisRed kidney beanPHA-L126Non-specific after neuraminidase treatment.Galß4GlcNAcß6(GlcNAc ß2Manα3)Manα3Yes
Ricinus communisCastor beanRCA-I, RCA 120120Non-specific after neuraminidase treatment.GalNo
Sambucus nigraElderberrySNA, EBL140Non-specific after neuraminidase treatment.Neu5Acα6Gal/GalNAcNo
Ulex europaeus IGorse, furzeUEA-I63o>A2αFucNo
Triticum vulgareWheat germWGA36A, B, OGlcNAcYes
Wisteria floribundaJapanese wisteriaWFA116Non-specific after neuraminidase treatment.GlcNAcNo

Lectin conjugate products

LectinConjugateCat. No.SizeProvided in the vial
Arachis hypogaea (peanut) lectin (PNA)Alexa Fluor 488L214091 mgLyophilized
Alexa Fluor 568L324581 mgLyophilized
Alexa Fluor 594L324591 mgLyophilized
Alexa Fluor 647L324601 mgLyophilized
Concanavalin AAlexa Fluor 488C112525 mgLyophilized
Alexa Fluor 594C112535 mgLyophilized
Alexa Fluor 350C112545 mgLyophilized
Alexa Fluor 633C214025 mgLyophilized
Alexa Fluor 647C214215 mgLyophilized
Texas-RedC82510 mgLyophilized
Fluorescein (FITC)C82710 mgLyophilized
tetramethylrhodamine (TRITC)C86010 mgLyophilized
Concanavalin A, succinylatedAlexa Fluor 488C214015 mgLyophilized
Dolichos Biflorus Agglutinin (DBA)Fluorescein (FITC)L324742 mgLiquid (2mg/mL)
Glycine max (soybean) Lectin (SBA)Alexa Fluor 488L112721 mgLyophilized
Alexa Fluor 594L324621 mgLyophilized
Alexa Fluor 647L324631 mgLyophilized
Griffonia simplicifolia (Africa Shrub legume) Lectin (GSL-II)Alexa Fluor 488L214150.5mgLyophilized
Alexa Fluor 594L214160.5mgLyophilized
Alexa Fluor 647L324510.5mgLyophilized
Griffonia simplicifolia (Africa Shrub legume) Isolectin GS-IB4 of B subunits (GS-IB4, GSL-IB4)Alexa Fluor 488I214110.5mgLyophilized
Alexa Fluor 568I214120.5mgLyophilized
Alexa Fluor 594I214130.5mgLyophilized
DyLight 594L324730.5mgLiquid (1mg/mL)
Alexa Fluor 647I324500.5mgLyophilized
biotin-XX conjugateI214140.5mgLyophilized
Helix pomatia (edible snail) Lectin (HPA)Alexa Fluor 488L112711 mgLyophilized
Alexa Fluor 647L324541 mgLyophilized
Lens Culinaris Agglutinin (LCA)Fluorescein (FITC)L324755 mgLiquid (5mg/mL)
Lotus Tetragonolobus Lectin (LTL)Fluorescein (FITC)L324802 mgLiquid (2mg/mL)
Lycopersicon esculentum (Tomato) Lectin (LEL, LEA, TL)DyLight 488L324701 mgLiquid (1mg/mL)
DyLight 594L324711 mgLiquid (1mg/mL)
DyLight 649L324721 mgLiquid (1mg/mL)
Fluorescein (FITC)L324781 mgLiquid (1mg/mL)
Texas-RedL324821 mgLiquid (1mg/mL)
Phaseolus vulgaris (red kidney bean) Lectin (PHA-L)Alexa Fluor 488L112701 mgLyophilized
Alexa Fluor 594L324561 mgLyophilized
Ricinus Communis Agglutinin I (RCA I, RCA120)Fluorescein (FITC)L324775 mgLiquid (5mg/mL)
Sambucus Nigra Lectin (SNA, EBL)Fluorescein (FITC)L324792 mgLiquid (2mg/mL)
Ulex Europaeus Agglutinin I (UEA I)Fluorescein (FITC)L324762 mgLiquid (2mg/mL)
Wheat Germ Agglutinin (WGA)Alexa Fluor 350W112635 mgLyophilized
Alexa Fluor 488W112615 mgLyophilized
Alexa Fluor 555W324645 mgLyophilized
Alexa Fluor 594W112625 mgLyophilized
Alexa Fluor 633W214045 mgLyophilized
Alexa Fluor 647W324665 mgLyophilized
Alexa Fluor 680W324655 mgLyophilized
Oregon Green 488W67485 mgLyophilized
TetramethylrhodamineW8495 mgLyophilized
Texas Red-XW214051 mgLyophilized
FluoresceinW8345 mgLyophilized
Wheat Germ Agglutinin Sampler Kit - Four Fluorescent Conjugates, 1 mg each1 KitW70241 KitLyophilized
Wisteria Floribunda Lectin (WFA, WFL)Fluorescein (FITC)L324812 mgLiquid (2mg/mL)