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.
J Biol Chem
2008 May 30;28322:15250-7. doi: 10.1074/jbc.M708638200.
Show Gene links
Show Anatomy links
Gamma-aminobutyric acid (GABA) and pentobarbital induce different conformational rearrangements in the GABA A receptor alpha1 and beta2 pre-M1 regions.
Mercado J
,
Czajkowski C
.
???displayArticle.abstract???
Gamma-aminobutyric acid (GABA) binding to GABA(A) receptors (GABA(A)Rs) triggers conformational movements in the alpha(1) and beta(2) pre-M1 regions that are associated with channel gating. At high concentrations, the barbiturate pentobarbital opens GABA(A)R channels with similar conductances as GABA, suggesting that their open state structures are alike. Little, however, is known about the structural rearrangements induced by barbiturates. Here, we examined whether pentobarbital activation triggers movements in the GABA(A)R pre-M1 regions. Alpha(1)beta(2) GABA(A)Rs containing cysteine substitutions in the pre-M1 alpha(1) (K219C, K221C) and beta(2) (K213C, K215C) subunits were expressed in Xenopus oocytes and analyzed using two-electrode voltage clamp. The cysteine substitutions had little to no effect on GABA and pentobarbital EC(50) values. Tethering chemically diverse thiol-reactive methanethiosulfonate reagents onto alpha(1)K219C and alpha(1)K221C affected GABA- and pentobarbital-activated currents differently, suggesting that the pre-M1 structural elements important for GABA and pentobarbital current activation are distinct. Moreover, pentobarbital altered the rates of cysteine modification by methanethiosulfonate reagents differently than GABA. For alpha(1)K221Cbeta(2) receptors, pentobarbital decreased the rate of cysteine modification whereas GABA had no effect. For alpha(1)beta(2)K215C receptors, pentobarbital had no effect whereas GABA increased the modification rate. The competitive GABA antagonist SR-95531 and a low, non-activating concentration of pentobarbital did not alter their modification rates, suggesting that the GABA- and pentobarbital-mediated changes in rates reflect gating movements. Overall, the data indicate that the pre-M1 region is involved in both GABA- and pentobarbital-mediated gating transitions. Pentobarbital, however, triggers different movements in this region than GABA, suggesting their activation mechanisms differ.
Amin,
GABAA receptor needs two homologous domains of the beta-subunit for activation by GABA but not by pentobarbital.
1993, Pubmed,
Xenbase
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
Bali,
Defining the propofol binding site location on the GABAA receptor.
2004,
Pubmed
,
Xenbase
Belelli,
General anaesthetic action at transmitter-gated inhibitory amino acid receptors.
1999,
Pubmed
Belelli,
The interaction of the general anesthetic etomidate with the gamma-aminobutyric acid type A receptor is influenced by a single amino acid.
1997,
Pubmed
,
Xenbase
Boileau,
Molecular dissection of benzodiazepine binding and allosteric coupling using chimeric gamma-aminobutyric acidA receptor subunits.
1998,
Pubmed
,
Xenbase
Chakrapani,
Gating dynamics of the acetylcholine receptor extracellular domain.
2004,
Pubmed
Grosman,
Mapping the conformational wave of acetylcholine receptor channel gating.
2000,
Pubmed
Harrison,
Positive modulation of human gamma-aminobutyric acid type A and glycine receptors by the inhalation anesthetic isoflurane.
1993,
Pubmed
Holden,
Different residues in the GABA(A) receptor alpha 1T60-alpha 1K70 region mediate GABA and SR-95531 actions.
2002,
Pubmed
,
Xenbase
Jackson,
Single channel currents activated by gamma-aminobutyric acid, muscimol, and (-)-pentobarbital in cultured mouse spinal neurons.
1982,
Pubmed
Kloda,
Agonist-, antagonist-, and benzodiazepine-induced structural changes in the alpha1 Met113-Leu132 region of the GABAA receptor.
2007,
Pubmed
,
Xenbase
Lee,
Principal pathway coupling agonist binding to channel gating in nicotinic receptors.
2005,
Pubmed
Lema,
Modes and models of GABA(A) receptor gating.
2006,
Pubmed
Li,
Identification of a GABAA receptor anesthetic binding site at subunit interfaces by photolabeling with an etomidate analog.
2006,
Pubmed
Liman,
Subunit stoichiometry of a mammalian K+ channel determined by construction of multimeric cDNAs.
1992,
Pubmed
,
Xenbase
MacDonald,
Kinetic properties and regulation of GABAA receptor channels.
1992,
Pubmed
MacDonald,
Barbiturate regulation of kinetic properties of the GABAA receptor channel of mouse spinal neurones in culture.
1989,
Pubmed
Mathers,
(-)Pentobarbital opens ion channels of long duration in cultured mouse spinal neurons.
1980,
Pubmed
Mercado,
Charged residues in the alpha1 and beta2 pre-M1 regions involved in GABAA receptor activation.
2006,
Pubmed
,
Xenbase
Mihic,
Sites of alcohol and volatile anaesthetic action on GABA(A) and glycine receptors.
1997,
Pubmed
,
Xenbase
Mihic,
Inhibition of rho1 receptor GABAergic currents by alcohols and volatile anesthetics.
1996,
Pubmed
,
Xenbase
MONOD,
ON THE NATURE OF ALLOSTERIC TRANSITIONS: A PLAUSIBLE MODEL.
1965,
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
Newell,
The GABAA receptor alpha 1 subunit Pro174-Asp191 segment is involved in GABA binding and channel gating.
2003,
Pubmed
,
Xenbase
Olsen,
Drug interactions at the GABA receptor-ionophore complex.
1982,
Pubmed
Pascual,
State-dependent accessibility and electrostatic potential in the channel of the acetylcholine receptor. Inferences from rates of reaction of thiosulfonates with substituted cysteines in the M2 segment of the alpha subunit.
1998,
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
Rho,
Direct activation of GABAA receptors by barbiturates in cultured rat hippocampal neurons.
1996,
Pubmed
Robertson,
Potassium currents expressed from Drosophila and mouse eag cDNAs in Xenopus oocytes.
1996,
Pubmed
,
Xenbase
Rosen,
Channel opening by anesthetics and GABA induces similar changes in the GABAA receptor M2 segment.
2007,
Pubmed
Serafini,
Structural domains of the human GABAA receptor 3 subunit involved in the actions of pentobarbital.
2000,
Pubmed
Siegwart,
Molecular determinants for the action of general anesthetics at recombinant alpha(2)beta(3)gamma(2)gamma-aminobutyric acid(A) receptors.
2002,
Pubmed
Siegwart,
Mutational analysis of molecular requirements for the actions of general anaesthetics at the gamma-aminobutyric acidA receptor subtype, alpha1beta2gamma2.
2003,
Pubmed
Sigel,
Role of the conserved lysine residue in the middle of the predicted extracellular loop between M2 and M3 in the GABA(A) receptor.
1999,
Pubmed
,
Xenbase
Wagner,
Structure and dynamics of the GABA binding pocket: A narrowing cleft that constricts during activation.
2001,
Pubmed
,
Xenbase
Zeller,
Mapping the contribution of beta3-containing GABAA receptors to volatile and intravenous general anesthetic actions.
2007,
Pubmed
