  We discuss different mechanisms for curvature-induced domain formation in
multicomponent lipid membranes and present a theoretical model that allows us
to study the interplay between the domains. The model represents the membrane
by two coupled monolayers, which each carry an additional order parameter field
describing the local lipid composition. The spontaneous curvature of each
monolayer is coupled to the local composition, moreover, the lipid compositions
on opposing monolayers are coupled to each other. Using this model, we
calculate the phase behavior of the bilayer in mean-field approximation. The
resulting phase diagrams are surprisingly complex and reveal a variety of
phases and phase transitions, including a decorated microdomain phase where
nanodomains are aligned along the microdomain boundaries. Our results suggest
that external membrane tension can be used to control the lateral organization
of nanodomains (which might be associated with lipid "rafts") in a
multicomponent lipid bilayer.
