Seeing spots: complex phase behavior in simple membranes.
Liquid domains in model lipid bilayers are frequently studied as models of raft domains in cell plasma membranes. Micron-scale liquid domains are easily produced in vesicles composed of ternary mixtures of a high melting temperature lipid, a low melting temperature lipid, and cholesterol. Here, we describe the rich phase behavior observed in binary and ternary systems. We then discuss experimental challenges inherent in mapping phase diagrams of even simple lipid systems. For example, miscibility behavior varies with lipid type, lipid ratio, lipid oxidation, and level of impurity. Liquid domains are often circular, but can become noncircular when membranes are near critical points. Finally, we reflect on applications of phase diagrams in model systems to rafts in cell membranes.
Veatch
Sarah L
SL
Department of Physics, University of Washington, Seattle WA 98195, USA. sveatch@u.washington.edu
Keller
Sarah L
SL
D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D008560:Membrane Fluidity; D021962:Membrane Microdomains / Q000378:metabolism; D044367:Phase Transition
D008051:Lipid Bilayers; D008055:Lipids; D002784:Cholesterol