Affinity purified Solanum tuberosum lectin/agglutinin (STA/STL) is a hydroxyproline-rich glycoprotein. This lectin contains 50% carbohydrates, predominantly arabinose; and consists of two subunits. STA/STL binds oligomers of N-acetylglucosamine and some bacterial cell wall oligosaccharides containing N-acetylglucosamine and N-acetylmuramic acid. N-acetyllactosamine is a relatively weak inhibitor of hemagglutination induced by this lectin; though, it does not have a blood group specificity. Solanum tuberosum lectin has been shown to bind two and a half times more to colon cancer cells than normal tissue.
Cy5, when bound to Solanum tuberosum Lectin (STA/STL), 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.