I am interested in finding out how ion channels work, using electron microscopy to analyse their structures trapped in different physiological states. Current research focuses on the nicotinic acetylcholine receptor, the transmitter-gated ion channel at the nerve-muscle synapse. Images of isolated Torpedo postsynaptic membranes have now yielded a refined atomic model of this channel at 4? resolution. Freeze-trapping combined with imaging experiments are providing a mechanistic picture of how binding of acetylcholine opens the channel in near-atomic detail.