Intra-Membrane Surface Flow in Response to Protein Induced Spontaneous Curvature

Abstract

Lipid bilayers are unique in their biophysical properties. They are fluid in-plane and solid in bending. While traditional models use the Helfrich approach to model the elastic deformations of the bilayer membrane, these approaches only provide insight into the equilibrium configurations of the elastic deformations of the membrane. But many membrane deformations are dynamic and occur in response to protein binding. To capture these effects, it is important to model the viscoelastic properties of the lipid bilayer rather than the elastic bending alone. We have recently developed a model that accounts for the elastic bending behavior of the membrane and captures the flow of lipids on the surface of the membrane in response to a driving force.One important component in membrane deformations is the binding of proteins to the membrane surface. We use the viscous-elastic model of the bilayer membrane to capture the dynamics of membrane shape change in response to protein binding. The binding of proteins to the membrane is modeled as a kinetic process, and the surface density of the protein is assumed to be proportional to the spontaneous curvature of the membrane in that region. Numerical simulations show that binding of proteins changes the shape of the membrane and induces lipid flow from the boundaries. to allow for the increase in surface area of the membrane. Additionally, the surface pressure field evolves from a homogeneous distribution to an inhomogeneous distribution. Together,these results capture the dynamics of lipid flow and surface evolution in response to protein binding.