Polar residues in the second transmembrane domain of the rat P2X2 receptor that affect spontaneous gating, unitary conductance, and rectification

Cao, Lishuang, Broomhead, Helen, Young, Mark Thomas ORCID: https://orcid.org/0000-0002-9615-9002 and North, R. Alan 2009. Polar residues in the second transmembrane domain of the rat P2X2 receptor that affect spontaneous gating, unitary conductance, and rectification. Journal of Neuroscience 29 (45) , pp. 14257-14264. 10.1523/JNEUROSCI.4403-09.2009

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Abstract

Membrane ion channels activated by extracellular ATP (P2X receptors) are widely distributed in the nervous system. Their molecular architecture is fundamentally distinct from that of the nicotinic or glutamate receptor families. We have measured single-channel currents, spontaneous gating, and rectification of rat P2X2 receptor in which polar and charged residues of the second transmembrane domain (TM2) were systematically probed by mutagenesis. The results suggest that Asn333 and Asp349 lie respectively in external and internal vestibules. Substitutions at Asn333, Thr336, and Ser340 were particularly likely to cause spontaneously active channels. At Thr336, Thr339, and Ser340, the introduction of positive charge (Arg, Lys, or His, or Cys followed by treatment with 2-aminoethyl methanethiosulphonate) greatly enhanced outward currents, suggesting that side-chains of these three residues are exposed in the permeation pathway of the open channel. These functional findings are interpreted in the context of the recently reported 3.1 Å crystal structure of the zebrafish P2X4.1 receptor in the closed state. They imply that the gate is formed by residues Asn333 to Thr339 and that channel opening involves a counter-clockwise rotation and separation of the TM2 helices.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Biosciences
Subjects:	Q Science > Q Science (General) R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.jneurosci.org/site/misc/ifa_policies.xhtml#copyright (accessed 26/02/2014).
Publisher:	Society for Neuroscience
ISSN:	0270-6474
Date of First Compliant Deposit:	30 March 2016
Last Modified:	14 May 2023 16:20
URI:	https://orca.cardiff.ac.uk/id/eprint/24435

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