Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Proc Natl Acad Sci U S A
2008 Sep 09;10536:13604-9. doi: 10.1073/pnas.0801854105.
Show Gene links
Show Anatomy links
A conserved salt bridge critical for GABA(A) receptor function and loop C dynamics.
Venkatachalan SP
,
Czajkowski C
.
???displayArticle.abstract???
Chemical signaling in the brain involves rapid opening and closing of ligand gated ion channels (LGICs). LGICs are allosteric membrane proteins that transition between multiple conformational states (closed, open, and desensitized) in response to ligand binding. While structural models of cys-loop LGICs have been recently developed, our understanding of the protein movements underlying these conformational transitions is limited. Neurotransmitter binding is believed to initiate an inward capping movement of the loop C region of the ligand-binding site, which ultimately triggers channel gating. Here, we identify a critical intrasubunit salt bridge between conserved charged residues (betaE153, betaK196) in the GABA(A) receptor (GABA(A)R) that is involved in regulating loop C position. Charge reversals (E153K, K196E) increased the EC(50) for GABA and for the allosteric activators pentobarbital (PB) and propofol indicating that these residues are critical for channel activation, and charge swap (E153K-K196E) significantly rescued receptor function suggesting a functional electrostatic interaction. Mutant cycle analysis of alanine substitutions indicated that E153 and K196 are energetically coupled. By monitoring disulfide bond formation between cysteines substituted at these positions (E153C-K196C), we probed the mobility of loop C in resting and ligand-bound states. Disulfide bond formation was significantly reduced in the presence of GABA or PB suggesting that agonist activation of the GABA(A)R proceeds via restricting loop C mobility.
Akk,
Activation and block of recombinant GABA(A) receptors by pentobarbitone: a single-channel study.
2000, Pubmed
Akk,
Activation and block of recombinant GABA(A) receptors by pentobarbitone: a single-channel study.
2000,
Pubmed
Amin,
GABAA receptor needs two homologous domains of the beta-subunit for activation by GABA but not by pentobarbital.
1993,
Pubmed
,
Xenbase
Amin,
A single hydrophobic residue confers barbiturate sensitivity to gamma-aminobutyric acid type C receptor.
1999,
Pubmed
Brejc,
Crystal structure of an ACh-binding protein reveals the ligand-binding domain of nicotinic receptors.
2001,
Pubmed
Careaga,
Structure and dynamics of Escherichia coli chemosensory receptors. Engineered sulfhydryl studies.
1992,
Pubmed
Celie,
Nicotine and carbamylcholine binding to nicotinic acetylcholine receptors as studied in AChBP crystal structures.
2004,
Pubmed
Faiman,
On the choice of reference mutant states in the application of the double-mutant cycle method.
1996,
Pubmed
Farrant,
Variations on an inhibitory theme: phasic and tonic activation of GABA(A) receptors.
2005,
Pubmed
Gao,
Agonist-mediated conformational changes in acetylcholine-binding protein revealed by simulation and intrinsic tryptophan fluorescence.
2005,
Pubmed
Gao,
Solution NMR of acetylcholine binding protein reveals agonist-mediated conformational change of the C-loop.
2006,
Pubmed
Grutter,
An H-bond between two residues from different loops of the acetylcholine binding site contributes to the activation mechanism of nicotinic receptors.
2003,
Pubmed
Hansen,
Structures of Aplysia AChBP complexes with nicotinic agonists and antagonists reveal distinctive binding interfaces and conformations.
2005,
Pubmed
Henchman,
Ligand-induced conformational change in the alpha7 nicotinic receptor ligand binding domain.
2005,
Pubmed
Hidalgo,
Revealing the architecture of a K+ channel pore through mutant cycles with a peptide inhibitor.
1995,
Pubmed
,
Xenbase
Horovitz,
Double-mutant cycles: a powerful tool for analyzing protein structure and function.
1996,
Pubmed
Karlin,
Substituted-cysteine accessibility method.
1998,
Pubmed
Lee,
Principal pathway coupling agonist binding to channel gating in nicotinic receptors.
2005,
Pubmed
Liu,
Variable reactivity of an engineered cysteine at position 338 in cystic fibrosis transmembrane conductance regulator reflects different chemical states of the thiol.
2006,
Pubmed
,
Xenbase
McLaughlin,
Role of the outer beta-sheet in divalent cation modulation of alpha7 nicotinic receptors.
2006,
Pubmed
,
Xenbase
Mercado,
Charged residues in the alpha1 and beta2 pre-M1 regions involved in GABAA receptor activation.
2006,
Pubmed
,
Xenbase
Mercado,
Gamma-aminobutyric acid (GABA) and pentobarbital induce different conformational rearrangements in the GABA A receptor alpha1 and beta2 pre-M1 regions.
2008,
Pubmed
,
Xenbase
Mukhtasimova,
Initial coupling of binding to gating mediated by conserved residues in the muscle nicotinic receptor.
2005,
Pubmed
Newell,
Mutation of glutamate 155 of the GABAA receptor beta2 subunit produces a spontaneously open channel: a trigger for channel activation.
2004,
Pubmed
,
Xenbase
Pistis,
Complementary regulation of anaesthetic activation of human (alpha6beta3gamma2L) and Drosophila (RDL) GABA receptors by a single amino acid residue.
1999,
Pubmed
,
Xenbase
Purohit,
A stepwise mechanism for acetylcholine receptor channel gating.
2007,
Pubmed
Sadovsky,
Principles underlying energetic coupling along an allosteric communication trajectory of a voltage-activated K+ channel.
2007,
Pubmed
Schreiber,
The role of Glu73 of barnase in catalysis and the binding of barstar.
1997,
Pubmed
Serafini,
Structural domains of the human GABAA receptor 3 subunit involved in the actions of pentobarbital.
2000,
Pubmed
Sheldahl,
Molecular dynamics on a model for nascent high-density lipoprotein: role of salt bridges.
1999,
Pubmed
Shi,
Ligand-induced conformational changes in the acetylcholine-binding protein analyzed by hydrogen-deuterium exchange mass spectrometry.
2006,
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
Wagner,
Structure and dynamics of the GABA binding pocket: A narrowing cleft that constricts during activation.
2001,
Pubmed
,
Xenbase
Yifrach,
Energetics of pore opening in a voltage-gated K(+) channel.
2002,
Pubmed
,
Xenbase
