This lectin is a family of tetrameric glycoproteins consisting of combinations of A and B subunits similar in structure to PHA and GSL I. The dominant isolectins in our preparations appear to be B subunit-rich. VVL recognizes preferentially alpha- or beta-linked terminal N-acetylgalactosamine, especially a single alpha N-acetylgalactosamine residue linked to serine or threonine in a polypeptide (the “Tn antigen”). Evidence suggests that this lectin also may require specific amino acid sequences at the receptor site of glycosylation. The disaccharide galactosyl (a-1,3) N-acetylgalactosamine is also a potent inhibitor of this 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.