Agaricus bisporus agglutinin (ABA) is an affinity-purified tetramer composed of two to four isolectins. ABA has two distinct carbohydrate binding sites, one for galactose-ß-1,3-N-acetylgalactosamine and another for galactose-ß-1,3-N-acetylglucosamine. Agaricus bisporus has an anti-proliferative effect on cancerous cells. ABA can be internalized by clathrin-coated vesicles after binding to surface glycoproteins, thus making ABA an inhibitor of its nuclear import of signal-dependent proteins. Agaricus bisporus Lectin (ABA/ABL) is conjugated to ferritin, that has a molecular weight of 474,000 g/mol (all 24 subunits combined). Ferritin-conjugated ABA/ABL can be used to visualize localization of specific saccharide moieties and examine the distribution of plasma membrane glycoproteins. These conjugates can be viewed via electron microscopy.