Budding and Domain Shape Transformations in Mixed Lipid Films and Bilayer Membranes

Abstract

We study the stability and shapes of domains with spontaneous curvature in fluid films and membranes, embedded in a surrounding membrane with zero spontaneous curvature. These domains can result from the inclusion of an impurity in a fluid membrane, or from phase separation within the membrane. We show that for small but finite line and surface tensions and for finite spontaneous curvatures, an equilibrium phase of protruding circular domains is obtained at low impurity concentrations. At higher concentrations, we predict a transition from circular domains, or "caplets", to stripes. In both cases, we calculate the shapes of these domains within the Monge representation for the membrane shape. With increasing line tension, we show numerically that there is a budding transformation from stable protruding circular domains to spherical buds. We calculate the full phase diagram, and demonstrate a two triple points, of respectively bud-flat-caplet and flat-stripe-caplet coexistence.

14 pages, to appear in Phys Rev E

References in corpus (1)

• On the formation of caveolae and similar membrane invaginations

Cited by in corpus (15)

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• Pattern formation of phase-separated lipid domains in bilayer membranes
• General neck condition for the limit shape of budding vesicles
• A curvature-driven effective attraction in multicomponent membranes
• The Phase Behavior of Mixed Lipid Membranes in Presence of the Rippled Phase
• Domain formation in bicomponent vesicles induced by composition-curvature coupling
• Phase transitions and membrane stiffness in a class of asymmetric heterogeneous fluid membranes
• Lipid Domain Order and the Algebra of Morphology