Ceramide-Induced Lamellar Gel Phases in Fluid Cell Lipid Extracts.

The effects of increasing amounts of palmitoylceramide (pCer) on human red blood cell lipid membranes have been studied using atomic force microscopy of supported lipid bilayers, in both imaging (bilayer thickness) and force-spectroscopy (nanomechanical resistance) modes. Membranes appeared homogeneous with pCer concentrations up to 10 mol % because of the high concentration of cholesterol (Chol) present in the membrane (∼45 mol %). However, the presence of pCer at 30 mol % gave rise to a clearly distinguishable segregated phase with a nanomechanical resistance 7-fold higher than the continuous phase.