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

Lectin Source Common Abbreviation Unconjugated Molecular Wt. (kDa) Preferred Sugar Specificity Blood Group Specificity Mitogenic Activity
Arachis hypogaea Peanut PNA 110 T antigen (M, N) ß-gal(1->3)galNAc No
Canavalia ensiformis Canavalia ensiformis (jack bean) Con A 104 Non-specific after neuraminidase treatment. α-man, α-glc Yes
Canavalia ensiformis Canavalia ensiformis (jack bean) Succinylated Con A 56 Non-specific after neuraminidase treatment. α-man, α-glc Yes
Dolichos biflorus Horse gram DBA 111 A1 α-galNAc No
Glycine max Soybean SBA 120 A>O>B α>ßGalNAc Yes
Griffonia (Bandeiraea) simplicifolia I Isolectin B4 Africa Shrub legume GSL I - B4, GS-IB4 114 B αGal No
Griffonia (Bandeiraea) simplicifolia II Africa Shrub legume GSL II, BSL II, GS II 113 B>>A1 α or ß GalNAc No
Helix pomatia Edible snail HPA 79 A galNAc No
Lens culinaris Lentil LcH, LCA 50 Non-specific after neuraminidase treatment. αMan, αGlc Yes
Lotus tetragonolobus Asparagus pea Lotus 107 O<A2 αFuc Yes
Lycopersicon esculentum Tomato LEA, LEL, TL 71 Non-specific after neuraminidase treatment. (glcNAc)3 Yes
Phaseolus vulgaris Red kidney bean PHA-L 126 Non-specific after neuraminidase treatment. Galß4GlcNAcß6(GlcNAc ß2Manα3)Manα3 Yes
Ricinus communis Castor bean RCA-I, RCA 120 120 Non-specific after neuraminidase treatment. Gal No
Sambucus nigra Elderberry SNA, EBL 140 Non-specific after neuraminidase treatment. Neu5Acα6Gal/GalNAc No
Ulex europaeus I Gorse, furze UEA-I 63 o>A2 αFuc No
Triticum vulgare Wheat germ WGA 36 A, B, O GlcNAc Yes
Wisteria floribunda Japanese wisteria WFA 116 Non-specific after neuraminidase treatment. GlcNAc No


Lectin conjugate products

Lectin Conjugate Cat. No. Size Provided in the vial
Arachis hypogaea (peanut) lectin (PNA) Alexa Fluor 488 L21409 1 mg Lyophilized
Alexa Fluor 568 L32458 1 mg Lyophilized
Alexa Fluor 594 L32459 1 mg Lyophilized
Alexa Fluor 647 L32460 1 mg Lyophilized
Concanavalin A Alexa Fluor 488 C11252 5 mg Lyophilized
Alexa Fluor 594 C11253 5 mg Lyophilized
Alexa Fluor 350 C11254 5 mg Lyophilized
Alexa Fluor 633 C21402 5 mg Lyophilized
Alexa Fluor 647 C21421 5 mg Lyophilized
Texas-Red C825 10 mg Lyophilized
Fluorescein (FITC) C827 10 mg Lyophilized
tetramethylrhodamine (TRITC) C860 10 mg Lyophilized
Concanavalin A, succinylated Alexa Fluor 488 C21401 5 mg Lyophilized
Dolichos Biflorus Agglutinin (DBA) Fluorescein (FITC) L32474 2 mg Liquid (2mg/mL)
Glycine max (soybean) Lectin (SBA) Alexa Fluor 488 L11272 1 mg Lyophilized
Alexa Fluor 594 L32462 1 mg Lyophilized
Alexa Fluor 647 L32463 1 mg Lyophilized
Griffonia simplicifolia (Africa Shrub legume) Lectin (GSL-II) Alexa Fluor 488 L21415 0.5mg Lyophilized
Alexa Fluor 594 L21416 0.5mg Lyophilized
Alexa Fluor 647 L32451 0.5mg Lyophilized
Griffonia simplicifolia (Africa Shrub legume) Isolectin GS-IB4 of B subunits (GS-IB4, GSL-IB4) Alexa Fluor 488 I21411 0.5mg Lyophilized
Alexa Fluor 568 I21412 0.5mg Lyophilized
Alexa Fluor 594 I21413 0.5mg Lyophilized
DyLight 594 L32473 0.5mg Liquid (1mg/mL)
Alexa Fluor 647 I32450 0.5mg Lyophilized
biotin-XX conjugate I21414 0.5mg Lyophilized
Helix pomatia (edible snail) Lectin (HPA) Alexa Fluor 488 L11271 1 mg Lyophilized
Alexa Fluor 647 L32454 1 mg Lyophilized
Lens Culinaris Agglutinin (LCA) Fluorescein (FITC) L32475 5 mg Liquid (5mg/mL)
Lotus Tetragonolobus Lectin (LTL) Fluorescein (FITC) L32480 2 mg Liquid (2mg/mL)
Lycopersicon esculentum (Tomato) Lectin (LEL, LEA, TL) DyLight 488 L32470 1 mg Liquid (1mg/mL)
DyLight 594 L32471 1 mg Liquid (1mg/mL)
DyLight 649 L32472 1 mg Liquid (1mg/mL)
Fluorescein (FITC) L32478 1 mg Liquid (1mg/mL)
Texas-Red L32482 1 mg Liquid (1mg/mL)
Phaseolus vulgaris (red kidney bean) Lectin (PHA-L) Alexa Fluor 488 L11270 1 mg Lyophilized
Alexa Fluor 594 L32456 1 mg Lyophilized
Ricinus Communis Agglutinin I (RCA I, RCA120) Fluorescein (FITC) L32477 5 mg Liquid (5mg/mL)
Sambucus Nigra Lectin (SNA, EBL) Fluorescein (FITC) L32479 2 mg Liquid (2mg/mL)
Ulex Europaeus Agglutinin I (UEA I) Fluorescein (FITC) L32476 2 mg Liquid (2mg/mL)
Wheat Germ Agglutinin (WGA) Alexa Fluor 350 W11263 5 mg Lyophilized
Alexa Fluor 488 W11261 5 mg Lyophilized
Alexa Fluor 555 W32464 5 mg Lyophilized
Alexa Fluor 594 W11262 5 mg Lyophilized
Alexa Fluor 633 W21404 5 mg Lyophilized
Alexa Fluor 647 W32466 5 mg Lyophilized
Alexa Fluor 680 W32465 5 mg Lyophilized
Oregon Green 488 W6748 5 mg Lyophilized
Tetramethylrhodamine W849 5 mg Lyophilized
Texas Red-X W21405 1 mg Lyophilized
Fluorescein W834 5 mg Lyophilized
Wheat Germ Agglutinin Sampler Kit - Four Fluorescent Conjugates, 1 mg each 1 Kit W7024 1 Kit Lyophilized
Wisteria Floribunda Lectin (WFA, WFL) Fluorescein (FITC) L32481 2 mg Liquid (2mg/mL)