Identification of the Blood‐Group ABH‐Active Glycoprotein Components of Human Erythrocyte Membrane

TLDR: The different lectin-binding properties indicate a structural difference between the antigenic determinants of the sialoglycoproteins and of the other blood-group-active components, which could explain the controversy concerning the nature of the blood- group ABH antigens in glycoprotein of the erythrocyte membrane.

Abstract: The blood-group ABH-active components of the erythrocyte membrane were identified by incubation of polyacrylamide gels after electrophoresis with radio-iodinated blood-group-specific lectins. The anti-A and anti-B lectin of Bandeiraea simplicifolia bound to components from A1, AB and B erythrocytes but not A2 or O erythrocytes, whereas the opposite was observed for the anti-H lectin of Lotus tetragonolobus. Both lectins revealed as major blood-group-active components band 3 and the region of band 4.5, which was resolved into at least two components. Smaller amounts of the lectins were bound to the low-molecular-weight region and the dye front, which contained the poly(glycosyl)ceramides. In addition to these components, the B. simplicifolia lectin also bound to the sialoglycoprotein bands 1 and 2 (stained with periodic acid/Schiff). The distribution of bound radioactivity, as determined with this lectin was: Band 3, 22–25%; HIO4/Schiff band-1, 10–15%; band 4.5, 34–37%; HIO4/Schiff band-2, 12–15%; and the poly(glycosyl)ceramide region, 14–17%. The different lectin-binding properties indicate a structural difference between the antigenic determinants of the sialoglycoproteins and of the other blood-group-active components. It is suggested that the antigenic determinants in the sialoglycoproteins are of the alkali-labile type previously characterized, and that the carbohydrate chains of bands 3 and 4.5 correspond to the previously isolated alkali-stable poly(glycosyl)peptides. The detection of two different groups of glycoproteins could thus explain the controversy concerning the nature of the blood-group ABH antigens in glycoproteins of the erythrocyte membrane.