Ceramide-Induced Lamellar Gel Phases in Fluid Cell Lipid Extracts

• DOI: 10.1021/acs.langmuir.6b01579
• Publication Date: 2016-08-03T20:01:29Z
• Authors: Aritz B. García-A...; Hasna Ahyayauch; Jesús Sot; Pablo L. López-Go...; Alicia Alonso; Félix M. Goñi
• Keywords: Lamellar phase; Lipid raft; Lipid microdomain; Cell membrane

The effects of increasing amounts palmitoylceramide (pCer) on human red blood cell lipid membranes have been studied using atomic force microscopy supported bilayers, in both imaging (bilayer thickness) and force-spectroscopy (nanomechanical resistance) modes. Membranes appeared homogeneous with pCer concentrations up to 10 mol % because the high concentration cholesterol (Chol) present membrane (∼45 %). However, presence at 30 gave rise a clearly distinguishable segregated phase nanomechanical resistance 7-fold higher than continuous phase. These experiments were validated differential scanning calorimetry. Furthermore, Chol depletion bilayers caused domain generation originally samples, Chol-depleted stiffness significantly increased pCer. results point possibility different kinds transient noncompositionally constant, complex gel-like phases RBC rich Chol, contrast widespread opinion about displacements between pCer-enriched "gel-like" domains liquid-ordered "raft-like" Chol-enriched phases. Changes biophysical properties these governed by local modulation pCer:Chol ratios could be mechanism for fine-tuning as required.