Effect of membrane characteristics on phase separation and domain formation in cholesterol-lipid mixtures.
We examine, using an analytical mean-field model, the distribution of cholesterol in a lipid bilayer. The model accounts for the perturbation of lipid packing induced by the embedded cholesterol, in a manner similar to that of transmembrane proteins. We find that the membrane-induced interactions between embedded cholesterol molecules vary as a function of the cholesterol content. Thus, the effective lipid-cholesterol interaction is concentration-dependent. Moreover, it transitions from repulsive to attractive to repulsive as the cholesterol content increases. As the concentration of cholesterol in the bilayer exceeds a critical value, phase separation occurs. The coexistence between cholesterol-rich and cholesterol-poor domains is universal for any bilayer parameters, although the composition of the cholesterol-rich phase varies as a function of the lipid properties. Although we do not assume specific cholesterol-lipid interactions or the formation of a lipid-cholesterol cluster, we find that the composition of the cholesterol-rich domains is constant, independent of the cholesterol content in the bilayer.
Pata
Veena
V
Department of Chemical Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA.
Dan
Nily
N
D002784:Cholesterol / Q000737:chemistry*; D045424:Complex Mixtures / Q000737:chemistry; D003198:Computer Simulation; D008051:Lipid Bilayers / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008560:Membrane Fluidity; D021962:Membrane Microdomains / Q000737:chemistry*; D008567:Membranes, Artificial; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D044367:Phase Transition
D045424:Complex Mixtures; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008567:Membranes, Artificial; D002784:Cholesterol