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J. Biol. Chem., Vol. 283, Issue 41, 27426-27432, October 10, 2008

This Article Free via Author's Choice: AC AC Full Text Full Text (PDF) Supplemental Data AC All Versions of this Article: 283/41/27426    most recent M801049200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Xia, R. Articles by Jiang, L.-H. Search for Related Content PubMed PubMed Citation Articles by Xia, R. Articles by Jiang, L.-H. Social Bookmarking                      What's this?

Identification of Pore Residues Engaged in Determining Divalent Cationic Permeation in Transient Receptor Potential Melastatin Subtype Channel 2^*

From the Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom

The molecular basis for divalent cationic permeability in transient receptor potential melastatin subtype (TRPM) channels is not fully understood. Here we studied the roles of all eight acidic residues, glutamate or aspartate, and also the glutamine residue between pore helix and selectivity filter in the pore of TRPM2 channel. Mutants with alanine substitution in each of the acidic residues, except Glu-960 and Asp-987, formed functional channels. These channels exhibited similar Ca²⁺ and Mg²⁺ permeability to wild type channel, with the exception of the E1022A mutant, which displayed increased Mg²⁺ permeability. More conservative E960Q, E960D, and D987N mutations also led to loss of function. The D987E mutant was functional and showed greater Ca²⁺ permeability along with concentration-dependent inhibition of Na⁺-carrying currents by Ca²⁺. Incorporation of negative charge in place of Gln-981 between the pore helix and selectivity filter by changing it to glutamate, which is present in the more Ca²⁺-permeable TRPM channels, substantially increased Ca²⁺ permeability. Expression of concatemers linking wild type and E960D mutant subunits resulted in functional channels that exhibited reduced Ca²⁺ permeability. These data taken together suggest that Glu-960, Gln-981, Asp-987, and Glu-1022 residues are engaged in determining divalent cationic permeation properties of the TRPM2 channel.

Received for publication, February 8, 2008 , and in revised form, July 9, 2008.

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^* This work was supported by the Wellcome Trust (to L.-H. Jiang). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement"in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains five supplemental figures.

¹ A recipient of the UK Overseas Research Scholarship.

² A Royal Society visiting research fellow from the Shanghai Institute of Microsystems and Information Technology, Chinese Academy of Science, China.

³ A visiting scholar from the School of Medicine, Zhejiang University, China. Supported in part by a Worldwide Universities Network global exchange award.

⁴ A visiting scholar from and supported by School of Medicine, Shanghai Jiaotong University, China.

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⁵ To whom correspondence should be addressed. E-mail:: l.h.jiang{at}leeds.ac.uk.

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