Nicotinic acetylcholine receptors are ligand-gated ion channels that mediate fast chemical neurotransmission; here, the first X-ray crystal structure of a nicotinic receptor is reported, revealing how nicotine stabilizes the receptor in a non-conducting, desensitized conformation. Nicotinic acetylcholine receptors are ligand-gated ion channels that mediate fast chemical neurotransmission at the neuromuscular junction and have diverse signalling roles in the central nervous system. In this manuscript, the authors report the first X-ray crystal structure of the human α4β2 nicotinic receptor, the most abundant nicotinic subtype in the brain. In addition to representing the first high-resolution structure of a heteromeric member of the pentameric 'Cys-loop' receptor family, the structure was obtained in the presence of nicotine and reveals how this agonist stabilizes the receptor in a non-conducting, desensitized conformation. Nicotinic acetylcholine receptors are ligand-gated ion channels that mediate fast chemical neurotransmission at the neuromuscular junction and have diverse signalling roles in the central nervous system. The nicotinic receptor has been a model system for cell-surface receptors, and specifically for ligand-gated ion channels, for well over a century1,2. In addition to the receptors’ prominent roles in the development of the fields of pharmacology and neurobiology, nicotinic receptors are important therapeutic targets for neuromuscular disease, addiction, epilepsy and for neuromuscular blocking agents used during surgery2,3,4. The overall architecture of the receptor was described in landmark studies of the nicotinic receptor isolated from the electric organ of Torpedo marmorata5. Structures of a soluble ligand-binding domain have provided atomic-scale insights into receptor–ligand interactions6, while high-resolution structures of other members of the pentameric receptor superfamily provide touchstones for an emerging allosteric gating mechanism7. All available high-resolution structures are of homopentameric receptors. However, the vast majority of pentameric receptors (called Cys-loop receptors in eukaryotes) present physiologically are heteromeric. Here we present the X-ray crystallographic structure of the human α4β2 nicotinic receptor, the most abundant nicotinic subtype in the brain. This structure provides insights into the architectural principles governing ligand recognition, heteromer assembly, ion permeation and desensitization in this prototypical receptor class.

X-ray structure of the human α4β2 nicotinic receptor