Asymmetric phase diagram of a binary lipid mixture

Abstract

The plasma membranes of eukaryotic cells are asymmetric with respect to their lipid composition. Model membrane studies consistently find that simplified outer leaflet mixtures tend to separate into coexisting liquid phases in symmetric bilayers, while inner leaflet mixtures do not. Among the major unanswered questions is how the phase behavior of the two leaflets is coupled in an asymmetric bilayer. Mean field theory has been used to calculate asymmetric phase diagrams, where phase boundaries and tieline orientations depend on the relative strength of in-plane and out-of-plane lipid interaction energies.