Budding of domains in mixed bilayer membranes
J. Wolff, Institut Charles Sadron (UPR CNRS), Strasbourg
We propose a model that accounts for budding behavior of domains in lipid bilayers, where each of the bilayer leaflets has a coupling between its local curvature and local lipid composition. The compositional asymmetry between the two monolayers leads to an overall spontaneous curvature. The membrane free energy contains three contributions: bending energy, line tension, and a Landau free energy for a lateral phase separation. Within a mean-field treatment, we obtain various phase diagrams which contain fully-budded, dimpled and flat states.
In particular, for some range of membrane parameters, the phase diagrams exhibit a tri-critical behavior as well as three-phase coexistence region. The global phase diagrams can be divided into three types and are analyzed in terms of the curvature-composition coupling parameter and domain size.
Ref.: J.Wolff, S. Komura, D. Andelman, PRE 91, 012708 (2015)