Surface Area per Lipid Molecule in the Intact Membrane of the Human Red Cell

Abstract

MODELS for the structure of the red cell membrane vary according to the assessment of the area occupied by the lipids in the cell surface. In 1925, Gorter and Grendel¹ found the area of a monomolecular film of extracted lipids at an air–water interface to be twice that of the cell surface area and postulated a lipid bilayer in the membrane. Dervichian and Macheboeuf² used similar techniques and obtained a ratio of 1 : 1. Bar et al.³ found that the ratio depends on the surface pressure used in compressing the film: higher pressures lead to a lower area per lipid molecule and hence to a lower ratio of lipid area to membrane area, and lower pressures lead to a higher ratio. There is, however, little basis for deciding which pressure best represents the situation of the lipids in the intact membrane.