title: Interaction of human erythrocyte Band 3 with Ricinus communis agglutinin and other lectins.
abstract: Agglutination and competition studies suggest that human erythrocyte Band 3 can interact with both mannose/glucose- and galactose-specific lectins. Purified Band 3 reconstituted into lipid vesicles binds concanavalin A, but the nonspecific binding component, measured in the presence of alpha-methylmannoside, is very high. This glycoprotein also carries binding sites for the galactose-specific lectin Ricinus communis agglutinin. Binding was inhibited poorly by lactose, but much more effectively by desialylated fetuin glycopeptides, suggesting that the lectin recognizes a complex oligosaccharide sequence on Band 3. The glycoprotein bears two separate classes of binding sites for R. communis agglutinin. High-affinity binding sites exist which show strong positive cooperativity and correspond in number to the outward-facing Band 3 molecules. A low-affinity binding mode is abolished by 40% ethyleneglycol, suggesting the involvement of hydrophobic lectin-glycoprotein interactions. Studies on binding of R. communis agglutinin to human erythrocytes indicate positively cooperative binding to 7 X 10(5) very-high-affinity sites per cell, and lectin binding is completely inhibitable by lactose. Based on its binding characteristics in vesicles, it seems likely that Band 3 forms the major receptor for this lectin in human erythrocytes. Properties such as positive cooperativity thus appear to be a common feature of the interaction of Band 3 with a variety of lectins of different specificity, both in erythrocytes and lipid bilayers.
mesh_terms: D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism*; D001667:Binding, Competitive; D003208:Concanavalin A / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D037102:Lectins / Q000378:metabolism*; D008051:Lipid Bilayers / Q000378:metabolism; D037121:Plant Lectins
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D037102:Lectins; D008051:Lipid Bilayers; D037121:Plant Lectins; C017707:Ricinus communis agglutinin-1; D003208:Concanavalin A; C019558:succinylconcanavalin A