Heterogeneity of aggregates of the human erythrocyte membrane glycoproteins.

The crude red cell glycoproteins obtained by four different methods are compared. The most selective isolation of the major membrane glycoprotein (MN blood group glycoprotein) is achieved by the phenol-water extraction procedure. A different degree of aggregation of this glycoprotein in water and in various buffers is demonstrated. The gel filtration of the crude glycoprotein on a Sepharose 4B column in 0.05 M pyridine--acetate buffer of pH 5.3 gives four fractions with different chemical compostition and serologic properties. The fractions obtained are heterogenous in SDS-PAGE and represent different kinds of glycoprotein aggregates. The distribution of serologic activities in the fractions obtained indicates that A, B and I activities found in the crude prepration of red cell glycoprotein are not connected with MN glycoprotein.