Scaling of Lipid Membrane Rigidity with Domain Area Fraction
Elizabeth G. Kelley, Michihiro Nagao, Paul D. Butler
The elastic properties of cell membranes play a vital role in controlling the morphology changes necessary for cell processes such as endocytosis and cell division. These elastic properties are highly sensitive to the lipid composition and distribution within the membrane, as phase separation into coexisting lipid domains has been predicted to modulate the macroscopic membrane mechanical properties that are essential to cell function. Here we use neutron spin echo spectroscopy to show that the effective bending moduli, κeff, of model lipid membranes with coexisting gel and fluid domains directly depends on the area fraction of the gel phase. Our experimental results are in excellent agreement with theoretical predictions for heterogeneous lipid membranes and have important implications for understanding the effects of rigid inhomogeneties, such as lipid domains and integral membrane proteins, on the elasticity of biological membranes.