Extracellular ATP is able to activate two families of cell-surface receptors, one of which is the ligand-gated ion channel family of P2X receptors. This family of cation channels is distinct from the remainder of the ligand-gated ion channels, as they are constructed of three (usually homomeric) subunits each with two transmembrane domains. Amongst the P2X receptors, the P2X3 is associated particularly with synaptic transmission in the sensory system and has, therefore, attracted a lot of attention as a potential target for novel analgesics and/or bladder dysfunction therapies.
In this report [1], multiple crystal structures of the P2X3 receptor are described, which allow a novel insight into the gating of a ligand-gated ion channel during the rest-agonist activated-refractory cycle, as well as with antagonist bound.
[1] Mansoor et al. (2016). X-ray structures define human P2X3 receptor gating cycle and antagonist action. Nature 538:66-71. doi: 10.1038/nature19367. [PMID 27626375].
Comments by Steve Alexander
guidetopharmacology blog 
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