This lectin is a dimeric glycoprotein composed of two subunits of nearly identical size with each subunit having disulfide-linked chains and a binding site for α- or β-linkedN-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 α- or β-linked N-acetylglucosamine residues on the nonreducing terminal of oligosaccharides. Fluorescein labeled GSL II has an appropriate number of fluorochromes bound to provide the optimum staining characteristics for this lectin. This conjugate is supplied essentially free of unconjugated fluorochromes. The excitation maximum is at 495 nm and the emission maximum is at 515 nm.