Phytolacca americana

About the Lectin

Most plant lectins are concentrated in the seeds but several have been isolated from roots, bark, stems, and leaves. Pokeweed is unique in that strong mitogenic activity has been found in virtually all parts of the plant, including the root, leaves, berries, seed, and stem 1,2 . Variable hemagglutination has been associated with the extracts from different plant parts. A method for purifying a homogeneous protein was developed in the 1960’s and, with some modifications, is still in use today 3 . The purified protein is a hemagglutinin, a leucoagglutinin, and a potent mitogen. The pure lectin has been further separated into at least five isolectins 4 . All isolectins are mitogenic for murine T cells but only one of the isolectins is also mitogenic for murine B cells 4,5 . This particular isolectin also happens to be the most potent hemagglutinin. Using different procedure, a sixth isolectin, along with three others corresponding to some of the 5 isolectins normally isolated (but not the B-cell mitogen) has been isolated and sequenced 6 . The isolectins contain various repeats of the GlcNAc- binding cysteine-rich hevein domain, accounting for the lectins general reactivity with GluNAc- containing oligo-saccharides 7-9 . Pokeweed has been used as a mitogen for human peripheral blood lymphocytes. In comparative mitogenic studies, pokeweed has a transformation rate of only about 60% that of PHA-P, but this is accomplished with one-tenth as much protein 3 . The individual isolectins exhibit variable reactivity with carbohydrates. Oligomers of β(1,4)-linked GlcNAc are inhibitory for only two of the isolectins. These two isolectins, as well as a third, are also inhibited by poly-N-acetyllactosamine containing glycoproteins 10 . The purified pokeweed supplied by EY Laboratories contains a mixture of all five isolectins. The amount of each isolectin in the preparation will vary depending on the season the roots are harvested as well as the region in which they are grown.


  1. Farnes, P., et al. (1964) Lancet. 2 : 1100-1101.
  2. Rosen, S. D., et al. (1974) Nature. 252 (128) : 149-151.
  3. Borjeson, J., et al. (1966) J. Exp. Med. 124 : 859-872.
  4. Waxdal, M. J. (1974) Biochemistry. 13 : 3671-3677.
  5. Yokoyama, K., et al. (1976) Biochim. Biophys. Acta.427 : 443-452.
  6. Kino, M., et al. (1995) Biosci. Biotech. Biochem. 59 : 683-59 688.
  7. Yamaguchi, K.I., et al. (1995) Biosci. Biotech. Biochem. 59 : 1384-1385.
  8. Yamaguchi, K.I., et al. (1996) Biosci. Biotech. Biochem. 60 : 1380-1382.
  9. Yamaguchi, K.I., et al. (1997) Biosci. Biotech. Biochem. 61 : 690-698.
  10. Irimura, T. and Nicholson, G. L. (1983) Carbohydrate Res. 120 : 187-195.

Product Characteristics

Buffer 0.01M Phosphate – 0.15M NaCl, pH 7.2-7.4.
Blood Group Nonspecific after neuraminidase treatment of the blood cells.
Activity Less than 0.5 μg/ml will agglutinate neuraminidase treated human red blood cells.
Inhibitory Carbohydrate Oligomers of β(1,4)-linked N‑acetyl‑D‑glucosamine, N-acetyllactosamine.
Molecular Weight The individual isolectins have molecular weights between 19-31,000 Da. Either 1 or 2 bands of 30,000 and 50,000 appear on SDS-PAGE.
Caution Pokeweed may promote an allergic reaction response in sensitive individuals. Be extremely careful when handling any of the pokeweed products.