Remarks on the spatial structure of the external segment of glycophorin A.

A model of the possible structure of the N-terminal part of glycophorin A is suggested. According to this model, in isotonic salt solutions of physiologic pH the peptide chain of the extracellular segment of glycophorin A is arranged parallel to the membrane with its carbohydrate side chains orientated perpendicularly to the lipid bilayer. Decreases of the pH or of the ionic strength result in a structural remodeling of this segment, there is at the very least a partial detachment of the glycosylated peptide backbone from the membrane's lipid layer.