Further studies on the membrane glycoprotein defects of S--s--and En(a--)-erythrocytes.

Sodium dodecylsulfate polyacrylamide gel electrophoretic methods were applied to S--s--and En(a--) red cells as well as to erythrocytes from individuals being heterozygous for these defects. The results demonstrate more conclusively than previous data, that the glycosylated part of the MN glycoprotein is lakcing in En(a--) red cell membranes. S--s--U--erythrocytes either lack the Ss glycoprotein completely or contain a defective molecule which is devoid of the glycosylated part. Conversely, S--s--U+ cells exhibit small amounts of Ss glycoprotein which could only be detected when large amounts of extracted glycoproteins were separated. It is shown that this molecule possesses the 'N' antigenic determinant.