QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: mol.106.026658v1 70/4/1159    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wilkinson, W. J. Articles by North, R. A. Search for Related Content PubMed PubMed Citation Articles by Wilkinson, W. J. Articles by North, R. A.

Accelerated Communication

Role of Ectodomain Lysines in the Subunits of the Heteromeric P2X_2/3 Receptor

Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom (W.J.W., R.A.N.); and Department of Biomedical Science, University of Sheffield, Sheffield United Kingdom (L.-H.J., A.S.)

Lysine residues near each end of the receptor ectodomain (in rat P2X₂ Lys⁶⁹ and Lys³⁰⁸) have been implicated in ATP binding to P2X receptors. We recorded membrane currents from human embryonic kidney cells expressing P2X subunits and found that lysine-to-alanine substitutions at equivalent positions in the P2X₃ receptor (Lys⁶³ and Lys²⁹⁹) also prevented channel function. Heteromeric P2X_2/3 receptors are formed when P2X₂ and P2X₃ subunits are expressed together; they can be distinguished by their relatively sustained response to β-methylene-ATP. By coexpression of wild-type P2X₃ and mutated P2X₂ subunit, we found that the heteromeric P2X_2/3 channel functioned normally when either lysine in the P2X₂ subunit was mutated to alanine (i.e., [K69A] or [K308A]) but not when both lysines were mutated to alanine (i.e., [K69A, K308A]). However, coexpression of wild-type P2X₂ with a mutated P2X₃ subunit ([K68A] or [K299A]) produced no functional heteromers. The rescue of the single lysine mutant P2X₂ subunit by wild-type P2X₃ (but not the converse) suggests that the heteromeric channel contains one P2X₂ and two P2X₃ subunits and that the receptor functions essentially normally as long as two subunits are not mutated. The failure to rescue function in the P2X₂ subunit with both lysines mutated by wild-type P2X₃ suggests that these residues from two different subunits interact in agonist binding or channel opening.

Address correspondence to: R. Alan North, Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK. E-mail: r.a.north{at}manchester.ac.uk

This article has been cited by other articles:

				J. A. Sim, H. E. Broomhead, and R. A. North Ectodomain Lysines and Suramin Block of P2X1 Receptors J. Biol. Chem., October 31, 2008; 283(44): 29841 - 29846. [Abstract] [Full Text] [PDF]

				R. Karoly, A. Mike, P. Illes, and Z. Gerevich The Unusual State-Dependent Affinity of P2X3 Receptors Can Be Explained by an Allosteric Two-Open-State Model Mol. Pharmacol., January 1, 2008; 73(1): 224 - 234. [Abstract] [Full Text] [PDF]

				X. Liu, A. Surprenant, H.-J. Mao, S. Roger, R. Xia, H. Bradley, and L.-H. Jiang Identification of Key Residues Coordinating Functional Inhibition of P2X7 Receptors by Zinc and Copper Mol. Pharmacol., January 1, 2008; 73(1): 252 - 259. [Abstract] [Full Text] [PDF]

				L. Cao, M. T. Young, H. E. Broomhead, S. J. Fountain, and R. A. North Thr339-to-Serine Substitution in Rat P2X2 Receptor Second Transmembrane Domain Causes Constitutive Opening and Indicates a Gating Role for Lys308 J. Neurosci., November 21, 2007; 27(47): 12916 - 12923. [Abstract] [Full Text] [PDF]

				R. K. Tittle, J. M. Power, and R. I. Hume A Histidine Scan to Probe the Flexibility of the Rat P2X2 Receptor Zinc-binding Site J. Biol. Chem., July 6, 2007; 282(27): 19526 - 19533. [Abstract] [Full Text] [PDF]

				B. Marquez-Klaka, J. Rettinger, Y. Bhargava, T. Eisele, and A. Nicke Identification of an Intersubunit Cross-Link between Substituted Cysteine Residues Located in the Putative ATP Binding Site of the P2X1 Receptor J. Neurosci., February 7, 2007; 27(6): 1456 - 1466. [Abstract] [Full Text] [PDF]