Bilayer Thickness Mismatch Controls Domain Size in Model Membranes
Top Cited Papers
- 22 February 2013
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 135 (18), 6853-6859
- https://doi.org/10.1021/ja3113615
Abstract
The observation of lateral phase separation in lipid bilayers has received considerable attention, especially in connection to lipid raft phenomena in cells. It is widely accepted that rafts play a central role in cellular processes, notably signal transduction. While micrometer-sized domains are observed with some model membrane mixtures, rafts much smaller than 100 nm—beyond the reach of optical microscopy—are now thought to exist, both in vitro and in vivo. We have used small-angle neutron scattering, a probe free technique, to measure the size of nanoscopic membrane domains in unilamellar vesicles with unprecedented accuracy. These experiments were performed using a four-component model system containing fixed proportions of cholesterol and the saturated phospholipid 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), mixed with varying amounts of the unsaturated phospholipids 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). We find that liquid domain size increases with the extent of acyl chain unsaturation (DOPC:POPC ratio). Furthermore, we find a direct correlation between domain size and the mismatch in bilayer thickness of the coexisting liquid-ordered and liquid-disordered phases, suggesting a dominant role for line tension in controlling domain size. While this result is expected from line tension theories, we provide the first experimental verification in free-floating bilayers. Importantly, we also find that changes in bilayer thickness, which accompany changes in the degree of lipid chain unsaturation, are entirely confined to the disordered phase. Together, these results suggest how the size of functional domains in homeothermic cells may be regulated through changes in lipid composition.This publication has 31 references indexed in Scilit:
- Control of a Nanoscopic-to-Macroscopic Transition: Modulated Phases in Four-Component DSPC/DOPC/POPC/Chol Giant Unilamellar VesiclesBiophysical Journal, 2011
- Comparison of Three Ternary Lipid Bilayer Mixtures: FRET and ESR Reveal NanodomainsBiophysical Journal, 2010
- Phase Separation in Biological Membranes: Integration of Theory and ExperimentAnnual Review of Biophysics, 2010
- Lipid Rafts As a Membrane-Organizing PrincipleScience, 2010
- Cholesterol-induced fluid membrane domains: A compendium of lipid-raft ternary phase diagramsBiochimica et Biophysica Acta (BBA) - Biomembranes, 2009
- Phase diagrams and lipid domains in multicomponent lipid bilayer mixturesBiochimica et Biophysica Acta (BBA) - Biomembranes, 2009
- Phase studies of model biomembranes: Complex behavior of DSPC/DOPC/CholesterolBiochimica et Biophysica Acta (BBA) - Biomembranes, 2007
- Scattering from laterally heterogeneous vesicles. II. The form factorJournal of Applied Crystallography, 2007
- “Entropic Traps” in the Kinetics of Phase Separation in Multicomponent Membranes Stabilize NanodomainsBiophysical Journal, 2006
- Line Tension and Interaction Energies of Membrane Rafts Calculated from Lipid Splay and TiltBiophysical Journal, 2005