Affinity purified Sambucus nigra lectin (EBL I+II, also known as SNA) is is composed of two ricin-related lectins. EBL I+II is a tetrameric glycoprotein with a recognition of the Neu5Ac(α2-6)Gal or GalNAc linkage in glycoconjugates.
EBL I+II is not blood group specific but it does agglutinate type A erythrocytes more strongly than either B or O cells. Trypsin treated erythrocytes react better than untreated cells. Neuraminidase treated erythrocytes react with this lectin due to the presence of terminal galactose resides. SNA has a broad specificity for both α- and β-linked galactose, as well as unrelated sugars such as fucose. It has been determined that the lectin does not bind to glycoproteins or glycolipids containing only terminal α(2,3)-linked sialic acid residues.
EBL I is composed of an A-chain with enzymatic activity and a B-chain with carbohydrate-binding activity. EBL II consists only of carbohydrate-binding B-chains. EBL I+II induces caspase-dependent apoptosis at low concentrations (nM) order, leading to typical symptoms of cell death in sensitive cells. This effect seems independent from the catalytic activity of the A-chain, but depends on the carbohydrate binding B-chain.
Texas Red is a red-fluorescent dye and when bound to Sambucus nigra Lectin (SNA/EBL I+II) can show the binding pattern of this lectin in cellular imaging applications. There is very little overlap between the emission spectra of Texas Red and FITC making this combination ideal for dual-labeling experiments. Rhodamine dyes, such as Texas Red, are more photostable and less sensitive to pH change when compared to other dyes such as fluorescein.