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. Colloidal gold can be used to visualize localization of specific saccharide moieties and examine the distribution of plasma membrane glycoproteins based on the binding pattern of Solanum tuberosum Lectin (STA/STL). Colloidal gold labeled lectins can be viewed via electron microscopy.