Binding occurs with carbohydrate structures containing alpha linked galactosamine. Lactose and other beta linked galactosides are poor inhibitors of binding. Tissue staining patterns using this lectin are clearly defined. Stratified squamous epithelium, endothelial cells and underlying basement membranes of blood vessels are intensely stained with PTL I. Pancreatic zymogen granules are also strongly labeled with the lectin.This biotinylated lectin conjugate is prepared from affinity-purified lectin and is optimally labeled with biotin. Essentially free of inactive lectin conjugate and containing no free biotin, this biotinylated lectin provides an ideal intermediate for examining glycoconjugates using the Biotin-Avidin System. First the biotin-labeled lectin is added, followed by the VECTASTAIN® ABC Reagent, Avidin D conjugate, or streptavidin derivative. Another possible application is in the isolation of lymphokines and other products of mitogenic stimulation.