Membrane-Mediated Interactions between Proteins in Multicomponent Bilayer Membranes

Abstract

Kahraman et al. [1] investigated how proteins in a single-component bilayer membrane interact through deformations of the membrane. However, because biological membranes are formed from lipids of different tail lengths, the model requires amendment. We expand this work by recasting their analysis of the free energy, defining a new quantity c to represent the local concentration of larger lipids around a neighborhood and introducing entropic terms associated with the differently-sized lipids into the free energy expression. There are now two Euler-Lagrange equations resulting from the revised free energy, which can be solved using analytic and numerical methods. These equations yield the membrane deformation field, which is then used to calculate the energy cost associated with insertion of proteins. Finally, we show that interactions between proteins in multicomponent bilayers are greatly diminished compared to interactions between proteins in single-component bilayers, and we consider the implications for phase separations of the proteins in the membrane.