Visualizing detergent resistant domains in model membranes with atomic force microscopy

Evidence is accumulating that in cell membranes microdomains exist, also re ferred to as rafts or detergent resistant membranes, In this study, atomic force microscopy is used to study supported lipid bilayers, consisting of a fluid phosphatidylcholine, sphingomyelin and cholesterol, Domains were vis ualized of which the morphology and size depended on the cholesterol concen tration, The presence of cholesterol was found to induce bilayer coupling. At 30 mol% cholesterol, a change in percolation phase was observed, and at 50 mol%, when both fluid lipids and solid lipids are saturated with cholest erol, phase separation was still observed. In addition, we were able to dir ectly visualize the resistance of domains against non-ionic detergent. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Sc ience B.V. All rights reserved.