  Motivated by single-molecule experiments on synaptic membrane protein
domains, we use a stochastic lattice model to study protein reaction and
diffusion processes in crowded membranes. We find that the stochastic
reaction-diffusion dynamics of synaptic proteins provide a simple physical
mechanism for collective fluctuations in synaptic domains, the molecular
turnover observed at synaptic domains, key features of the single-molecule
trajectories observed for synaptic proteins, and spatially inhomogeneous
protein lifetimes at the cell membrane. Our results suggest that central
aspects of the single-molecule and collective dynamics observed for membrane
protein domains can be understood in terms of stochastic reaction-diffusion
processes at the cell membrane.
