Blood group A activities of glycoprotein and glycolipid from human erythrocyte membranes.

It is known that ABO blood group substances in human erythrocyte membranes are sphingoglycolipids, but recently several authors have reported that the glycoproteins of the erythrocyte membranes also have ABO blood group activities in addition to MN blood group activities and virus hemagglutination inhibitor activity. We solubilized blood group A erythrocyte membranes with lithium diiodosalicylate and separated the glycoprotein fraction by phenol extraction and ethanol precipitation. This fraction was apparently not contaminated with glycolipid, but it showed weak blood group A activity. The activity of the glycoprotein of the erythrocyte membranes was one-sixth of that of the lgycolipid fraction from the same amount of membranes. The glycoprotein components were purified by Sephadex G-200 gel filtration in SDS. The main component isolated, PAS 1, still showed blood A activity.