Abstract
The lipid bilayer of the membrane of human erythrocytes from which most sialic acid residues on the outer surface had been removed was digested by phospholipase from outside the medium or treated by the incorpora-tion of exogenous amphiphilic lipid, then it was electrophoresed. After treat-ments that caused the additional exposure of the dissociable polar head group of the amphiphilic lipid to the outer medium, the electrophoretic mobility of the treated cells increased as the pH of the suspending medium rose. This show-ed that there was an increase in the negative charges in the immediate vicinity of the lipid bilayer surface of the membrane. The possible effect of the dissocia-tion of exposed head groups in the lipids on the morphology of the membrane is discussed.
