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Br J Pharmacol
2011 Feb 01;1623:673-87. doi: 10.1111/j.1476-5381.2010.01073.x.
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Disulphide trapping of the GABA(A) receptor reveals the importance of the coupling interface in the action of benzodiazepines.
Hanson SM
,
Czajkowski C
.
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Although the functional effects of benzodiazepines (BZDs) on GABA(A) receptors have been well characterized, the structural mechanism by which these modulators alter activation of the receptor by GABA is still undefined. We used disulphide trapping between engineered cysteines to probe BZD-induced conformational changes within the γ₂ subunit and at the α₁/γ₂ coupling interface (Loops 2, 7 and 9) of α₁β₂γ₂ GABA(A) receptors. Crosslinking γ₂ Loop 9 to γ₂β-strand 9 (via γ₂ S195C/F203C and γ₂ S187C/L206C) significantly decreased maximum potentiation by flurazepam, suggesting that modulation of GABA-induced current (I(GABA)) by flurazepam involves movements of γ₂ Loop 9 relative to γ₂β-strand 9. In contrast, tethering γ₂β-strand 9 to the γ₂ pre-M1 region (via γ₂S202C/S230C) significantly enhanced potentiation by both flurazepam and zolpidem, indicating γ₂S202C/S230C trapped the receptor in a more favourable conformation for positive modulation by BZDs. Intersubunit disulphide bonds formed at the α/γ coupling interface between α₁ Loop 2 and γ₂Loop 9 (α₁D56C/γ₂L198C) prevented flurazepam and zolpidem from efficiently modulating I(GABA) . Disulphide trapping α₁ Loop 2 (α₁D56C) to γ₂β-strand 1 (γ₂P64C) decreased maximal I(GABA) as well as flurazepam potentiation. None of the disulphide bonds affected the ability of the negative modulator, 3-carbomethoxy-4-ethyl-6,7-dimethoxy-β-carboline (DMCM), to inhibit I(GABA) . Positive modulation of GABA(A) receptors by BZDs requires reorganization of the loops in the α₁/γ₂ coupling interface. BZD-induced movements at the α/γ coupling interface likely synergize with rearrangements induced by GABA binding at the β/α subunit interfaces to enhance channel activation by GABA.
Akabas,
GABAA receptor structure-function studies: a reexamination in light of new acetylcholine receptor structures.
2004, Pubmed
Akabas,
GABAA receptor structure-function studies: a reexamination in light of new acetylcholine receptor structures.
2004,
Pubmed
Bali,
GABA-induced intersubunit conformational movement in the GABAA receptor alpha 1M1-beta 2M3 transmembrane subunit interface: experimental basis for homology modeling of an intravenous anesthetic binding site.
2009,
Pubmed
,
Xenbase
Bass,
Use of site-directed cysteine and disulfide chemistry to probe protein structure and dynamics: applications to soluble and transmembrane receptors of bacterial chemotaxis.
2007,
Pubmed
Baumann,
Forced subunit assembly in alpha1beta2gamma2 GABAA receptors. Insight into the absolute arrangement.
2002,
Pubmed
,
Xenbase
Bera,
Spontaneous thermal motion of the GABA(A) receptor M2 channel-lining segments.
2005,
Pubmed
,
Xenbase
Bocquet,
X-ray structure of a pentameric ligand-gated ion channel in an apparently open conformation.
2009,
Pubmed
Boileau,
The relative amount of cRNA coding for gamma2 subunits affects stimulation by benzodiazepines in GABA(A) receptors expressed in Xenopus oocytes.
2002,
Pubmed
,
Xenbase
Boileau,
Identification of transduction elements for benzodiazepine modulation of the GABA(A) receptor: three residues are required for allosteric coupling.
1999,
Pubmed
,
Xenbase
Boileau,
Molecular dissection of benzodiazepine binding and allosteric coupling using chimeric gamma-aminobutyric acidA receptor subunits.
1998,
Pubmed
,
Xenbase
Brejc,
Crystal structure of an ACh-binding protein reveals the ligand-binding domain of nicotinic receptors.
2001,
Pubmed
Campo-Soria,
Mechanism of action of benzodiazepines on GABAA receptors.
2006,
Pubmed
,
Xenbase
Careaga,
Structure and dynamics of Escherichia coli chemosensory receptors. Engineered sulfhydryl studies.
1992,
Pubmed
Downing,
Benzodiazepine modulation of partial agonist efficacy and spontaneously active GABA(A) receptors supports an allosteric model of modulation.
2005,
Pubmed
Eghbali,
Hippocampal GABA(A) channel conductance increased by diazepam.
1997,
Pubmed
Hanson,
Structural mechanisms underlying benzodiazepine modulation of the GABA(A) receptor.
2008,
Pubmed
,
Xenbase
Hanson,
Structural requirements for eszopiclone and zolpidem binding to the gamma-aminobutyric acid type-A (GABAA) receptor are different.
2008,
Pubmed
Hilf,
Structure of a potentially open state of a proton-activated pentameric ligand-gated ion channel.
2009,
Pubmed
Horenstein,
Protein mobility and GABA-induced conformational changes in GABA(A) receptor pore-lining M2 segment.
2001,
Pubmed
,
Xenbase
Horenstein,
Differential protein mobility of the gamma-aminobutyric acid, type A, receptor alpha and beta subunit channel-lining segments.
2005,
Pubmed
Jansen,
State-dependent cross-linking of the M2 and M3 segments: functional basis for the alignment of GABAA and acetylcholine receptor M3 segments.
2006,
Pubmed
,
Xenbase
Karlin,
Substituted-cysteine accessibility method.
1998,
Pubmed
Kosolapov,
Folding of the voltage-gated K+ channel T1 recognition domain.
2003,
Pubmed
,
Xenbase
Lavoie,
Direct evidence for diazepam modulation of GABAA receptor microscopic affinity.
1996,
Pubmed
Lu,
Pegylation: a method for assessing topological accessibilities in Kv1.3.
2001,
Pubmed
,
Xenbase
Mellor,
Frequency-dependent actions of benzodiazepines on GABAA receptors in cultured murine cerebellar granule cells.
1997,
Pubmed
Mercado,
Charged residues in the alpha1 and beta2 pre-M1 regions involved in GABAA receptor activation.
2006,
Pubmed
,
Xenbase
Miller,
Molecular basis for zinc potentiation at strychnine-sensitive glycine receptors.
2005,
Pubmed
Miyazawa,
Structure and gating mechanism of the acetylcholine receptor pore.
2003,
Pubmed
NULL,
Guide to Receptors and Channels (GRAC), 4th Edition.
2009,
Pubmed
Negroiu,
Folding and maturation of tyrosinase-related protein-1 are regulated by the post-translational formation of disulfide bonds and by N-glycan processing.
2000,
Pubmed
Rogers,
Benzodiazepine and beta-carboline regulation of single GABAA receptor channels of mouse spinal neurones in culture.
1994,
Pubmed
Rosen,
Channel opening by anesthetics and GABA induces similar changes in the GABAA receptor M2 segment.
2007,
Pubmed
Rüsch,
Classic benzodiazepines modulate the open-close equilibrium in alpha1beta2gamma2L gamma-aminobutyric acid type A receptors.
2005,
Pubmed
,
Xenbase
Shelness,
Role of intramolecular disulfide bond formation in the assembly and secretion of apolipoprotein B-100-containing lipoproteins.
1996,
Pubmed
Sigel,
Mapping of the benzodiazepine recognition site on GABA(A) receptors.
2002,
Pubmed
Sine,
Recent advances in Cys-loop receptor structure and function.
2006,
Pubmed
Unwin,
Refined structure of the nicotinic acetylcholine receptor at 4A resolution.
2005,
Pubmed
Venkatachalan,
Optimized expression vector for ion channel studies in Xenopus oocytes and mammalian cells using alfalfa mosaic virus.
2007,
Pubmed
,
Xenbase
Xu,
Identification of channel-lining residues in the M2 membrane-spanning segment of the GABA(A) receptor alpha1 subunit.
1996,
Pubmed
,
Xenbase
Yang,
Closed-state cross-linking of adjacent beta1 subunits in alpha1beta1 GABAa receptors via introduced 6' cysteines.
2007,
Pubmed
