  The plasma membrane of human red blood cells consists of a lipid bilayer
attached to a regular network of underlying cytoskeletal polymers. We model
this system at a dynamic coarse-grained level, treating the bilayer as an
elastic sheet and the cytoskeletal network as a series of phantom entropic
springs. In contrast to prior simulation efforts, we explicitly account for
dynamics of the cytoskeletal network, both via motion of the protein anchors
that attach the cytoskeleton to the bilayer and through breaking and
reconnection of individual cytoskeletal filaments. Simulation results are
explained in the context of a simple mean-field percolation model and
comparison is made to experimental measurements of red blood cell fluctuation
amplitudes.
