Ultrastructural and chemical analysis of the outer membrane leaflet of the human red blood cell.

Structural and biochemical analysis of the outer membrane leaflet of human erythrocytes freeze-fractured on positively charged supports showed that glycophorin A is its major constituent. Two classes of intramembrane particles can be discriminated on the external fracture face: those which are high but small in diameter and those which are low and large or elongated. The presence of small amount of band 3 protein in the outer membrane leaflet cannot be ruled out; it could be contained in the class of 'high' intramembrane particles on the external fracture face.