Many of the functions of membranes are carried out by proteins associated with them. A knowledge of atomic-detail membrane protein structures and dynamics is required for a full understanding of these functions. We briefly discuss recent progress in this field using modelling and simulation. One of the best characterised membrane proteins, bacteriorhodopsin, undergoes dynamical transitions with temperature. Here we present preliminary results of molecular dynamics simulation of this protein as a function of temperature, indicating the presence of dynamical transitions at approximately the temperatures seen experimentally.