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

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

This Article Full Text Full Text (PDF) Submit an eLetter 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 Web of Science 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 Web of Science (40) Citing Articles via Google Scholar Google Scholar Articles by Boileau, A. J. Articles by Czajkowski, C. Search for Related Content PubMed PubMed Citation Articles by Boileau, A. J. Articles by Czajkowski, C. Pubmed/NCBI databases Compound via MeSH Substance via MeSH

 Previous Article  |  Next Article 

The Journal of Neuroscience, December 1, 1999, 19(23):10213-10220

Identification of Transduction Elements for Benzodiazepine Modulation of the GABA_A Receptor: Three Residues Are Required for Allosteric Coupling

Andrew J. Boileau and Cynthia Czajkowski

Department of Physiology, University of Wisconsin-Madison, Madison, Wisconsin 53706

Modulation of GABA_A receptors by benzodiazepines (BZDs) is believed to involve two distinct steps: a recognition step in which BZDs bind and a conformational transition step in which the affinity of the receptor for GABA changes. Previously, using ₂/₁ chimeric subunits (), we demonstrated that although the N-terminal 167 ₂ amino acid residues confer high-affinity BZD binding, other ₂ domains couple BZD binding to potentiation of the GABA-mediated Cl current (I_GABA). To determine which ₂ regions couple binding to potentiation, we generated s with longer N-terminal ₂ segments for voltage-clamp experiments in Xenopus oocytes. Chimeras containing greater than the N-terminal 167 ₂ residues showed incremental gains in maximal potentiation for diazepam enhancement of I_GABA. Residues in ₂199-236, ₂224-236 (pre-M1), and particularly ₂257-297 (M2 and surrounding loops) are important for BZD potentiation. For several positive BZD modulators tested, the same regions restored potentiation of I_GABA. In contrast, -carboline inverse-agonism was unaltered in chimeric receptors, suggesting that structural determinants for positive and negative BZD allosteric modulation are different. Dissection of the ₂257-297 domain revealed that three residues in concert, ₂T281, ₂I282 (M2 channel vestibule), and ₂S291 (M2-M3 loop) are necessary to impart full BZD potentiation to chimeric receptors. Thus, these residues participate in coupling distant BZD-binding events to conformational changes in the GABA_A receptor. The location of these novel residues provides insight into the mechanisms underlying allosteric coupling for other members of the ligand-gated ion channel superfamily.

Key words: GABA; GABA_A receptor; benzodiazepines; benzodiazepine-binding site; allosteric coupling; chimeric subunits; mutagenesis; inverse agonist; positive modulation; subunit; subunit; M2 domain; M2-M3 loop; Xenopus oocytes

---

Copyright © 1999 Society for Neuroscience  0270-6474/99/192310213-08$05.00/0

This article has been cited by other articles:

				P. Belujon, J. Baufreton, L. Grandoso, E. Boue-Grabot, T.F.C. Batten, L. Ugedo, M. Garret, and A. I. Taupignon Inhibitory Transmission in Locus Coeruleus Neurons Expressing GABAA Receptor Epsilon Subunit Has a Number of Unique Properties J Neurophysiol, October 1, 2009; 102(4): 2312 - 2325. [Abstract] [Full Text] [PDF]

				L. M. Sharkey and C. Czajkowski Individually Monitoring Ligand-Induced Changes in the Structure of the GABAA Receptor at Benzodiazepine Binding Site and Non-Binding-Site Interfaces Mol. Pharmacol., July 1, 2008; 74(1): 203 - 212. [Abstract] [Full Text] [PDF]

				H.-J. Feng, G. C. Mathews, C. Kao, and R. L. Macdonald Alterations of GABAA-Receptor Function and Allosteric Modulation During Development of Status Epilepticus J Neurophysiol, March 1, 2008; 99(3): 1285 - 1293. [Abstract] [Full Text] [PDF]

				X.-Q. Hu and R. W. Peoples Arginine 246 of the Pretransmembrane Domain 1 Region Alters 2,2,2-Trichloroethanol Action in the 5-Hydroxytryptamine3A Receptor J. Pharmacol. Exp. Ther., March 1, 2008; 324(3): 1011 - 1018. [Abstract] [Full Text] [PDF]

				C. L. Padgett and S. C. R. Lummis The F-loop of the GABAA Receptor {gamma}2 Subunit Contributes to Benzodiazepine Modulation J. Biol. Chem., February 1, 2008; 283(5): 2702 - 2708. [Abstract] [Full Text] [PDF]

				Y. Chen, K. Reilly, and Y. Chang Evolutionarily Conserved Allosteric Network in the Cys Loop Family of Ligand-gated Ion Channels Revealed by Statistical Covariance Analyses J. Biol. Chem., June 30, 2006; 281(26): 18184 - 18192. [Abstract] [Full Text] [PDF]

				J. Mercado and C. Czajkowski Charged Residues in the {alpha}1 and beta2 Pre-M1 Regions Involved in GABAA Receptor Activation J. Neurosci., February 15, 2006; 26(7): 2031 - 2040. [Abstract] [Full Text] [PDF]

				A. J. Boileau, R. A. Pearce, and C. Czajkowski Tandem Subunits Effectively Constrain GABAA Receptor Stoichiometry and Recapitulate Receptor Kinetics But Are Insensitive to GABAA Receptor-Associated Protein J. Neurosci., December 7, 2005; 25(49): 11219 - 11230. [Abstract] [Full Text] [PDF]

				M. Ernst, S. Bruckner, S. Boresch, and W. Sieghart Comparative Models of GABAA Receptor Extracellular and Transmembrane Domains: Important Insights in Pharmacology and Function Mol. Pharmacol., November 1, 2005; 68(5): 1291 - 1300. [Abstract] [Full Text] [PDF]

				D. M. Jones-Davis, L. Song, M. J. Gallagher, and R. L. Macdonald Structural Determinants of Benzodiazepine Allosteric Regulation of GABAA Receptor Currents J. Neurosci., August 31, 2005; 25(35): 8056 - 8065. [Abstract] [Full Text] [PDF]

				J. W. Lynch Molecular Structure and Function of the Glycine Receptor Chloride Channel Physiol Rev, October 1, 2004; 84(4): 1051 - 1095. [Abstract] [Full Text] [PDF]

				N.-L. R. Han, J. D. Clements, and J. W. Lynch Comparison of Taurine- and Glycine-induced Conformational Changes in the M2-M3 Domain of the Glycine Receptor J. Biol. Chem., May 7, 2004; 279(19): 19559 - 19565. [Abstract] [Full Text] [PDF]

				A. K. Bera, M. Chatav, and M. H. Akabas GABAA Receptor M2-M3 Loop Secondary Structure and Changes in Accessibility during Channel Gating J. Biol. Chem., November 1, 2002; 277(45): 43002 - 43010. [Abstract] [Full Text] [PDF]

				M. Scheller and S. A. Forman Coupled and Uncoupled Gating and Desensitization Effects by Pore Domain Mutations in GABAA Receptors J. Neurosci., October 1, 2002; 22(19): 8411 - 8421. [Abstract] [Full Text] [PDF]

				S.-A. Thompson, P. B. Wingrove, L. Connelly, P. J. Whiting, and K. A. Wafford Tracazolate Reveals a Novel Type of Allosteric Interaction with Recombinant gamma -Aminobutyric AcidA Receptors Mol. Pharmacol., April 1, 2002; 61(4): 861 - 869. [Abstract] [Full Text] [PDF]

				J. A. Teissere and C. Czajkowski A {beta}-Strand in the {gamma}2 Subunit Lines the Benzodiazepine Binding Site of the GABAA Receptor: Structural Rearrangements Detected during Channel Gating J. Neurosci., July 15, 2001; 21(14): 4977 - 4986. [Abstract] [Full Text] [PDF]

				J. W. Lynch, N.-L. R. Han, J. Haddrill, K. D. Pierce, and P. R. Schofield The Surface Accessibility of the Glycine Receptor M2-M3 Loop Is Increased in the Channel Open State J. Neurosci., April 15, 2001; 21(8): 2589 - 2599. [Abstract] [Full Text] [PDF]

				N. Nagaya and R. L Macdonald Two {gamma}2L subunit domains confer low Zn2+ sensitivity to ternary GABAA receptors J. Physiol., April 1, 2001; 532(1): 17 - 30. [Abstract] [Full Text] [PDF]

				D. B. Williams and M. H. Akabas Benzodiazepines Induce a Conformational Change in the Region of the gamma -Aminobutyric Acid Type A Receptor alpha 1-Subunit M3 Membrane-Spanning Segment Mol. Pharmacol., November 1, 2000; 58(5): 1129 - 1136. [Abstract] [Full Text]

				S. Supplisson and D. Chesnoy-Marchais Glycine Receptor beta Subunits Play a Critical Role in Potentiation of Glycine Responses by ICS-205,930 Mol. Pharmacol., October 1, 2000; 58(4): 763 - 770. [Abstract] [Full Text]

				A. J. Boileau, J. G. Newell, and C. Czajkowski GABAA Receptor beta 2 Tyr97 and Leu99 Line the GABA-binding Site. INSIGHTS INTO MECHANISMS OF AGONIST AND ANTAGONIST ACTIONS J. Biol. Chem., January 18, 2002; 277(4): 2931 - 2937. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help