Nicotinic acetylcholine receptors (AChR) and their relatives mediate rapid chemical
transmission throughout the nervous system, yet their atomic structures remain elusive. Here
we use lysine scanning mutagenesis to determine the orientation of residue side chains
toward core hydrophobic or surface hydrophilic environments and use this information to
build a structural model of the ligand binding region of the AChR from adult human muscle.
The resulting side-chain orientations allow assignment of residue equivalence between …