Morphological characterization of the erythrocyte membrane related to myxovirus receptors.

The receptor of myxoviral hemagglutinins is defined by terminal sialic acid residues of the major sialoglycoprotein (glycophorin) of the human erythrocyte membrane. A number of lectins and antibodies are suitable to specifically label this molecule. The proposed association of glycophorin with the structures revealed as intramembrane particles (IMP) on freeze-fractured membranes rests only on indirect evidence; IMP are not composed of glycophorin alone but glycophorin may be a component of them in association with other integral membrane proteins and/or lipids. Mapping experiments employing limulin, a lectin specific for sialic acids, and anti-glycophorin are described. These experiments demonstrate a lack of association of glycophorin and the IMP.