The Receptor Proteins for Concanavalin A and Lens culinaris Phytohemagglutinin in the Membrane of the Human Erythrocyte

Human erythrocyte membranes were extracted with 0.1 mM ethylenediaminetetraacetate, pH 8.0, the residue was dissolved in Triton X-100, and the soluble fraction was applied to Sepharose derivatives of concanavalin A (Con A) or the phytohemagglutinin from Lens culinaris (LCPHA).Examination of the material retained by the insolubilized lectins and subsequently eluted with a-methyl mannoside reveals that the principal high affinity receptor for Con A is the minor glycoprotein (also called Band III and Component a).This protein is also thought to be the agent responsible for anion transport across the membrane of the human red blood cell.LCPHA is capable of binding the above polypeptide and the major sialoglycoprotein.Evidence is given to show that this binding is specific.The lectins retain quantitatively different fractions of the minor glycoprotein, the remainder of the protein being unretarded.It is suggested that this behavior may reflect heterogeneity in the carbohydrate moiety of the protein.