Studies on the membrane glycoprotein defect of En(a-) erythrocytes. I. Biochemical aspects.

Discontinuous sodium dodecylsulphate-polyacrylamide gel electrophoresis, followed by periodic acid/Schiff or Coomassie staining and densitometry, spectrophotometric and gas-liquid chromatographic carbohydrate analyses as well as heterophile agglutinins are employed to study the nature of the membrane glycoprotein defect in En(a-) erythrocytes from Finland and England, heterozygous Ena red cells from Finland and the erythrocytes of two individuals from Switzerland. The results suggest that En(a-) cells lack the major membrane sialoglycoprotein, the so-called MN glycoprotein. Heterozygous Ena erythrocytes from Finland and those from Switzerland have only about half of the normal amount of MN glycoprotein. The molecular weight of the major Coomassie staining membrane protein (component III) is increased by approx. 5000 and 3000 daltons in En(a-) and the other red cells respectively. Some aspects of this membrane defect are discussed.