Lectin-associated proteins from the seeds of Leguminosae.

The seeds of Pisum sativum (pea), Canavalia ensiformis, Vicia faba, Vicia sativa, and Ricinus communis were shown to contain proteins which are associated to the respective lectins (lectin binders). The lectin binders from Pisum sativum and Canavalia ensiformis were studied more closely. Both are single proteins not resembling the variety of membrane glycoproteins found in animals and plants which bind to lectins. The pea lectin binder is a tetrameric glycoprotein composed of identical subunits of the Mr 51 000. Its interaction with the lectin is abolished by acidic buffers or by glucose. The Concanavalin A binder, which does not contain sugar, is composed of one kind of subunit, Mr of 35 000. As in the case of the pea lectin binder, glucose and acid dissociate the lectin-lectin binder complex, but in contrast to the pea lectin binder low NaCl concentrations also cause this effect. During germination and growth, the Concanavalin A binder appears in the roots.