Recombination of human erythrocyte apoprotein and lipid. II. Visualization of apoprotein‐lipid bilayer complex by freeze‐etching

Bilayers of human erythrocyte apoprotein‐lipid complexes were made by dipping a mica plate through monolayers of the complex formed at the air‐water interface. Stearic acid and erythrocyte lipid alone served as controls. Freeze‐fracture images of the complex at high lipid surface pressures (30 dynes/cm) showed particles (average diameter, 109 Å ± 18 Å) similar to those of erythrocyte ghosts (average diameter, 102 Å ± 19 Å). Control surfaces were smooth. We conclude that part or all of the protein molecule penetrated into the lipid bilayer and that erythrocyte apoprotein‐lipid complexes yield fracture faces similar to the native erythrocyte membrane.