Griffonia (Bandeiraea) Simplicifolia Lectin I (GSL I, BSL I), Fluorescein, 5 mg. GSL I is a family of glycoproteins with molecular weights of approximately 114 kDa. There are two types of subunits, termed A and B, with slightly different molecular weights. These subunits combine to form tetrameric structures, resulting in five isolectins. The A-rich lectin preferentially agglutinates blood group A erythrocytes, appearing to be specific for alpha-N-acetylgalactosamine residues, while the B-rich lectin preferentially agglutinates blood group B cells and is specific for alpha-galactose residues. Vector Laboratories GSL I is a mixture of the five isolectins. GSL I has been reported to bind several glycoproteins including laminin. This product has an appropriate number of fluorochromes bound to provide the optimum staining characteristics of this lectin and is supplied essentially free of unconjugated fluorochromes. The excitation maximum is at 495 nm, and the emission maximum is at 515 nm.