title: Morphological phase diagram for lipid membrane domains with entropic tension.
abstract: Circular domains in phase-separated lipid vesicles with symmetric leaflet composition commonly exhibit three stable morphologies: flat, dimpled, and budded. However, stable dimples (i.e., partially budded domains) present a puzzle since simple elastic theories of domain shape predict that only flat and spherical budded domains are mechanically stable in the absence of spontaneous curvature. We argue that this inconsistency arises from the failure of the constant surface tension ensemble to properly account for the effect of entropic bending fluctuations. Formulating membrane elasticity within an entropic tension ensemble, wherein tension represents the free energy cost of extracting membrane area from thermal bending of the membrane, we calculate a morphological phase diagram that contains regions of mechanical stability for each of the flat, dimpled, and budded domain morphologies.
authors.affiliation: Department of Mechanical and Aerospace Engineering, and California NanoSystems Institute, University of California, Los Angeles, California 90095, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Rim
authors.forename: T S
authors.initials: TS
authors.lastname: Ursell
authors.forename: R
authors.initials: R
authors.lastname: Phillips
authors.forename: W S
authors.initials: WS
authors.lastname: Klug
mesh_terms: D002462:Cell Membrane / Q000737:chemistry*; D019277:Entropy; D008563:Membrane Lipids / Q000737:chemistry*; D044366:Transition Temperature
chemical_list: D008563:Membrane Lipids