Agaricus bisporus

About the Lectin

Two lectins with a similar specificity for cell surface glycoproteins are found in the commercial mushroom. These isolectins, which are referred to as PHA-A and PHA-B, react strongly with all blood types. Trypsin treatment of erythrocytes decreases lectin binding to the cell surface. The O-linked glycopeptide released by trypsin is a potent inhibitor of both of the isolectins. Removal of the terminal sialic acid residue from the glycopeptide increases its inhibitory potency 8-fold. This is in agreement with blood agglutination studies performed at EY Laboratories. Periodiate or β-galactosidase treatment of the trypsin released glycopeptide destroys all inhibitory activity. The trypsin released N-linked glycopeptide is not inhibitory for the mushroom isolectins. Normal human lymphocytes contain 12.7 million receptors / cell for the isolectins, while patients with chronic lymphocytic leukemia have only 2.8 million receptors / cell 1 . Simple sugars are very poor inhibitors of the isolectins, however, a galactose residue appears to play a major role in lectin binding. Evidently the sugar linkage is also important since the N-linked glycopeptide is not inhibitory while the O-linked glycopeptide is a potent inhibitor. The cell receptor for the isolectins has the structure Galactose-GalNAc-serine (or threonine). The lectins isolated from the commercial mushroom, A. bisporus, differ from the lectin isolated from the wild meadow mushroom, Agaricus campestris 2 . The wild mushroom lectin is mitogenic for lymphocytes, while neither of the isolectins from A. bisporus exhibit mitogenic activity. The lectin has been shown to bind to O-linked glycans of IgA subclasses, and may be useful to assess their glycosylation state 3,4 . FITC-labeled ABA shows characteristics staining pattern changes during maturation of rat spermatogenic cells 5 .

REFERENCES

  1. Present, C.A. and Kornfeld, S. (1972). J. Biol. Chem.247: 6937.
  2. Young, N.M., et al. (1971). J. Biol. Chem. 246: 1596.
  3. Irazoqui, F. J., et al. (1992) J. Immun. Methods. 156 : 199-204.
  4. Irazoqui, F. J., et al. (1997) Glycoconj. J. 14 : 313-319.
  5. Wine, R. N. and Chapin, R. E. (1997) J. Andrology 18 : 71-79.

Product Characteristics

Buffer 0.01M Phosphate – 0.15M NaCl, pH 7.2-7.4.
Blood Group Non-specific. O>A, B.
Activity 5-10 μg/ml will agglutinate type A or B cells. 2 μg/ml will agglutinate type O cells. Less than 0.5 μg/ml will agglutinate neuraminidase treated erythrocytes.
Inhibitory Carbohydrate β-D-Galactose (nominally). The lectin recognizes the structure Gal-GalNAc-serine (or threonine).
Molecular Weight Heterogeneous by SDS-PAGE. One band of MW=24,000 and several bands between 50-90,000 Da is typical.