Styphnolobium japonicum agglutinin (SJA) is affinity purified from Japanese pagoda tree seeds. It consists of two subunits. The subunits can be separated into two subfractions, a D-galactose/N-acetyl-D-galactosamine specific lectin (B-SJA-I) and a D-mannose/D-glucose specific lectin (B-SJA-II). SJA has an isoelectric point between pH 4.9 and pH 5.6 and a carbohydrate specificity towards βGalNAc. This lectin elutes with the sugar GalNAc.
SJA agglutinates all blood group types but has greater affinity for A erythrocytes than of B types, than of O (-SA) types. Binding experiments of the lectin with frozen sections of human kidneys shows specific binding to the endothelia in specimens from blood groups B or AB, thus indicating a D-galactose/N-acetyl-D-galactosamine receptor specificity. SJA lacks mitogenic and immune-suppressive activity.
Cy5, when bound to Styphnolobium japonicum Lectin (SJA), can show the binding pattern of this lectin in cellular imaging and flow cytometry. The excitation wavelength required for Cy5 to fluoresce is high enough to avoid overlap with most other fluorochromes, making it useful for dual-labeling experiments. Because of this high excitation, there is typically less background from autofluorescence of biological specimens.