The pre‐M1 segment of the α1 subunit is a transduction element in the activation of the GABAA receptor
- 8 August 2006
- journal article
- Published by Wiley in The Journal of Physiology
- Vol. 575 (1), 11-22
- https://doi.org/10.1113/jphysiol.2005.102756
Abstract
The binding of the neurotransmitter GABA induces conformational changes in the GABAA receptor (GABAAR), leading to the opening of a gate that controls ion permeation through an integral transmembrane pore. A number of structural elements within each subunit, located near the membrane interface, are believed to undergo relative movements during this activation process. In this study, we explored the functional role of the beta-10 strand (pre-M1 segment), which connects the extracellular domain to the transmembrane domain. In alpha1beta2gamma2s GABAARs, analysis of the 12 residues of the beta-10 strand in the alpha1 subunit proximal to the first transmembrane domain identified two residues, alpha1V212 and alpha1K220, in which mutations produced rightward shifts in the GABA concentration-response relationship and also reduced the relative efficacy of the partial agonist, piperidine-4-sulphonic acid. Ultra-fast agonist techniques were applied to mutant alpha1(K220A)beta2gamma2s GABAARs and revealed that the macroscopic functional deficit in this mutant could be attributed to a slowing of the opening rate constant, from approximately 1500 s(-1) in wild-type (WT) channels to approximately 730 s(-1) in the mutant channels, and a reduction in the time spent in the active state for the mutant. These changes were accompanied by a decrease in agonist affinity, with half-maximal activation rates achieved at 0.77 mM GABA in WT and 1.4 mM GABA in the alpha1(K220A)beta2gamma2s channels. The beta-10 strand (pre-M1 segment) emerges, from this and other studies, as a key functional component in the activation of the GABAAR.Keywords
This publication has 48 references indexed in Scilit:
- Modes and models of GABAA receptor gatingThe Journal of Physiology, 2006
- Charged Residues in the α1and β2Pre-M1 Regions Involved in GABAAReceptor ActivationJournal of Neuroscience, 2006
- Refined Structure of the Nicotinic Acetylcholine Receptor at 4Å ResolutionJournal of Molecular Biology, 2004
- Arginine 222 in the Pre-transmembrane Domain 1 of 5-HT3A Receptors Links Agonist Binding to Channel GatingPublished by Elsevier BV ,2003
- The GABAA Receptor α1 Subunit Pro174–Asp191 Segment Is Involved in GABA Binding and Channel GatingJournal of Biological Chemistry, 2003
- Forced Subunit Assembly in α1β2γ2 GABAAReceptors: INSIGHT INTO THE ABSOLUTE ARRANGEMENTJournal of Biological Chemistry, 2002
- Modulation of GABAA receptor channel gating by pentobarbitalThe Journal of Physiology, 2001
- Properties of human glycine receptors containing the hyperekplexia mutation α1(K276E), expressed in Xenopus oocytesThe Journal of Physiology, 1998
- GABAA receptor needs two homologous domains of the & beta;-subunit for activation by GABA but not by pentobarbitalNature, 1993