Sambucus nigra Lectin (SNA/EBL I) is an isolectin isolated from elderberry bark and purified by affinity chromatography. SNA I belongs to the group of type 2 ribosome-inactivating proteins and is composed of an A-chain with enzymatic activity and a B-chain with carbohydrate-binding activity. It has specificity for α2,6-linked sialic acid residues, and elutes with the sugar lactose. SNA I can induce apoptosis through the caspase-dependent pathway at low concentrations. This effect depends on the carbohydrate binding of the B-chain and is independent from the catalytic activity of the A-chain.
Cy3 can be used to visualize the binding pattern of Sambucus nigra Lectin (SNA/EBL I) in cellular imaging and flow cytometry. Cy3 is more photostable than many other fluorophores and can be seen with TRITC filter sets. It is commonly combined with green-fluorescent dyes for dual-labeling.