Reactions of erythrocyte glycoproteins and their degradation products with various anti-I sera.
Three fractions of erythrocyte glycoproteins obtained from Sepharose 4-B chromatography were tested for I activity with ten serologically differentiated anti-I sera. The most active was fraction I, eluted at the void volume and containing the lowest amount of alkali-labile oligosaccharide chains. The desialization of glycoproteins increased their activity toward anti-I-s and anti-I-D sera, and did not change or decreased the activity toward anti-I-F sera. The most abundant fraction II (major sialoglycoprotein of erythrocyte membranes) showed no or only a very weak I activity, but I-active glycopeptides were isolated from products of digestion of fraction II with trypsin. The major product of digestion, sialoglycopeptide IIT-2 showed I activity only after alkaline elimination of alkali-labile oligosaccharide chains. The results indicate  that I receptors are present in hindered form on apparently I-inactive components of erythrocyte membrane.
D000468:Alkalies; D000918:Antibody Specificity; D001666:Binding Sites, Antibody; D001789:Blood Group Antigens; D001894:Borohydrides; D002462:Cell Membrane / Q000276:immunology; D002850:Chromatography, Gel; D004912:Erythrocytes / Q000276:immunology*; D006020:Glycopeptides / Q000302:isolation & purification; D006023:Glycoproteins / Q000097:blood; D006385:Hemagglutination Inhibition Tests; D007106:Immune Sera; D012794:Sialic Acids / Q000032:analysis; D014357:Trypsin
D000468:Alkalies; D001789:Blood Group Antigens; D001894:Borohydrides; D006020:Glycopeptides; D006023:Glycoproteins; D007106:Immune Sera; D012794:Sialic Acids; D014357:Trypsin