isolated from Griffonia (Bandeiraea) simplicifolia seeds This lectin is a tetrameric glycoprotein composed of four subunits of nearly identical size. Each 30,000 dalton subunit has a binding site for alpha- or beta-linked N-acetylglucosamine residues. Unlike other N-acetylglucosamine specific lectins, increasing the number of N-acetylglucosamine residues beyond two does not improve affinity. GSL II has been reported to be unique in its ability to recognize exclusively alpha- or beta-linked N-acetylglucosamine residues on the nonreducing terminal of oligosaccharides.