Three families of ligand-activated ion channels mediate synaptic communication between excitable cells in mammals. For pentameric channels related to nicotinic acetylcholine receptors and tetrameric channels like glutamate receptors, the pore-forming and gate regions have been studied extensively. In contrast, little is known about the structure of trimeric P2X receptor channels, a family of channels that are activated by ATP and serve crucial roles in neuronal signaling, pain transmission and inflammation. To identify the pore-forming and gate regions within P2X receptor channels, we introduced cysteine residues throughout the two transmembrane (TM) segments and studied their accessibility to thiol reactive compounds and ions. Our results show that the TM2 helix lines the central ion conduction pore, that the TM1 helix is positioned peripheral to TM2, and that the flow of ions is minimized in the closed state by a gate formed by the external region of TM2.

Project Start
Project End
Budget Start
Budget End
Support Year
4
Fiscal Year
2010
Total Cost
$811,445
Indirect Cost
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Li, Mufeng; Toombes, Gilman E S; Silberberg, Shai D et al. (2015) Physical basis of apparent pore dilation of ATP-activated P2X receptor channels. Nat Neurosci 18:1577-83
Heymann, Gabriel; Dai, Jian; Li, Mufeng et al. (2013) Inter- and intrasubunit interactions between transmembrane helices in the open state of P2X receptor channels. Proc Natl Acad Sci U S A 110:E4045-54
Li, Mufeng; Silberberg, Shai D; Swartz, Kenton J (2013) Subtype-specific control of P2X receptor channel signaling by ATP and Mg2+. Proc Natl Acad Sci U S A 110:E3455-63
Kawate, Toshimitsu; Robertson, Janice L; Li, Mufeng et al. (2011) Ion access pathway to the transmembrane pore in P2X receptor channels. J Gen Physiol 137:579-90
Silberberg, Shai D; Swartz, Kenton J (2009) Structural biology: Trimeric ion-channel design. Nature 460:580-1
Li, Mufeng; Chang, Tsg-Hui; Silberberg, Shai D et al. (2008) Gating the pore of P2X receptor channels. Nat Neurosci 11:883-7
Silberberg, Shai D; Li, Mufeng; Swartz, Kenton J (2007) Ivermectin Interaction with transmembrane helices reveals widespread rearrangements during opening of P2X receptor channels. Neuron 54:263-74