Molecular blueprint of allosteric binding sites in a homologue of the agonist-binding domain of the α7 nicotinic acetylcholine receptor

In this study we take advantage of a recently described chimera of the α7 nicotinic acetylcholine receptor (nAChR) and acetylcholine binding protein (AChBP), termed α7-AChBP. To date, more than 70 crystal structures have been determined for AChBP in complex with ligands that occupy the orthosteric binding site. Here, we use an innovative screening strategy to discover molecular fragments that occupy allosteric binding sites. In combination with X-ray crystallography we determine a molecular blueprint of three different allosteric sites in α7-AChBP. Using electrophysiological recordings on the human α7 nAChR we demonstrate that each of the three sites is involved in allosteric modulation of the receptor. Our study contributes to understanding the sites of allosteric binding in ion channels.