Comparative modeling of GABAA receptors: limits, insights, future developments

Ernst, Margot; Brauchart, D; Boresch, Stefan; Sieghart, Werner

doi:10.1016/s0306-4522(03)00288-4

Cited by 148 publications

(185 citation statements)

References 55 publications

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“…The mutation ␣1H109C, however, caused a spontaneous cross-link of GABA A receptor subunits even in receptors composed of ␣1H109C and wild-type ␤3 and ␥2 subunits and thus in the absence of a mutated ␥2 subunit as a possible cross-link partner. 3 In the present study, this surprising observation was investigated in detail. It was demonstrated that the spontaneous disulfide bond formation occurred between two mutated ␣1 subunits during an early stage of assembly and that functional GABA A receptors could be formed despite the presence of a disulfide bond between two opposing subunits.…”

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confidence: 70%

“…After validation, a total of seven well scoring models (one per alignment) of the GABA A receptor extracellular domain were used to predict the segments that participate in interface formation. Despite the high uncertainty that is associated with amino acid side chain positions at most interface-forming regions (13,14), predictions were made with the program WHAT IF (32) on the possible formation of disulfide bridges.…”

Section: Culture and Transfection Of Hek 293 Cells For Binding Studiementioning

confidence: 99%

“…GABA A receptors are the targets of action of a variety of pharmacologically and clinically important drugs, such as benzodiazepines, barbiturates, steroids, anesthetics, and convulsants. These drugs modulate GABA-induced chloride ion flux by interacting with distinct allosteric binding sites at these receptors (2,3).…”

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confidence: 99%

“…Recombinant receptor studies (5)(6)(7)(8) as well as studies investigating the subunit composition of GABA A receptors in the brain (9,10) indicated that the vast majority of GABA A receptors found are composed of two ␣, two ␤, and one ␥ subunit. Biochemical studies (5,11,12) as well as modeling of the GABA A receptor extracellular domain (13) according to the structure of the acetylcholinebinding protein (14) indicated the absolute arrangement of the subunits in GABA A receptors (Fig. 1A).…”

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confidence: 99%

“…In a previous study, we used the comparative models developed by our group (13) for predicting amino acid residues in ␣1 and ␥2 subunits that might form direct contacts with each other (24). These residues were mutated to cysteines, and a possible disulfide bond formation between mutated subunits was investigated.…”

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confidence: 99%

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Spontaneous Cross-link of Mutated α1 Subunits during GABAA Receptor Assembly

Sarto-Jackson

Furtmueller

Ernst

et al. 2007

Journal of Biological Chemistry

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␥-Aminobutyric acid, type A (GABA A ) receptor ␣1 subunits containing a cysteine mutation at a position in the channel mouth (H109C) surprisingly formed a spontaneous cross-link with each other in receptors composed of ␣1H109C, ␤3, and ␥2 subunits. Cross-linking of two ␣1H109C subunits did not significantly change the affinity of [ 3 H]muscimol or [ 3 H]Ro15-1788 binding in ␣1H109C␤3␥2 receptors, but GABA displayed a reduced potency for activating chloride currents. On reduction of the disulfide bond, however, GABA activation as well as diazepam modulation was similar in mutated and wild-type receptors, suggesting that these receptors exhibited the same subunit stoichiometry and arrangement. Disulfide bonds could not be reoxidized by copper phenanthroline after having been reduced in completely assembled receptors, suggesting that cross-linking can only occur at an early stage of assembly. The cross-link of ␣1H109C subunits and the subsequent transport of the resulting homodimers to the cell surface caused a reduction of the intracellular pool of ␣1H109C subunits and a reduced formation of completely assembled receptors. The formation of ␣1H109C homodimers as well as of correctly assembled GABA A receptors containing cross-linked ␣1H109C subunits could indicate that homodimerization of ␣1 subunits via contacts located in the channel mouth might be one starting point of GABA A receptor assembly. Alternatively the assembly mechanism might have started with the formation of heterodimers followed by a cross-link of mutated ␣1 subunits at the heterotrimeric stage. The formation of cross-linked ␣1H109C homodimers would then have occurred independently in a separate pathway.GABA, 2 quantitatively the most important inhibitory neurotransmitter in the central nervous system, mediates fast synaptic inhibition by opening the chloride ion channel intrinsic to GABA A receptors (1). GABA A receptors are the targets of action of a variety of pharmacologically and clinically important drugs, such as benzodiazepines, barbiturates, steroids, anesthetics, and convulsants. These drugs modulate GABA-induced chloride ion flux by interacting with distinct allosteric binding sites at these receptors (2, 3).GABA A receptors are composed of five subunits (4, 5) that can belong to different subunit classes. Recombinant receptor studies (5-8) as well as studies investigating the subunit composition of GABA A receptors in the brain (9, 10) indicated that the vast majority of GABA A receptors found are composed of two ␣, two ␤, and one ␥ subunit. Biochemical studies (5,11,12) as well as modeling of the GABA A receptor extracellular domain (13) according to the structure of the acetylcholinebinding protein (14) indicated the absolute arrangement of the subunits in GABA A receptors (Fig. 1A).To achieve the correct order of subunits around the pore, each subunit must be able to discriminate between different subunits and to interact with its neighbors via specific high affinity contact sites. Several amino acid sequences have been identified th...

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confidence: 70%

Section: Culture and Transfection Of Hek 293 Cells For Binding Studiementioning

confidence: 99%

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confidence: 99%

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confidence: 99%

mentioning

confidence: 99%

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Spontaneous Cross-link of Mutated α1 Subunits during GABAA Receptor Assembly

Sarto-Jackson

Furtmueller

Ernst

et al. 2007

Journal of Biological Chemistry

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GABAand Glutamate Receptor Ligands and their Therapeutic Potential inCNSDisorders

Madsen¹,

Bräuner‐Osborne²,

Greenwood³

et al. 2010

Pharmaceutical Sciences Encyclopedia

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The complex functions of the mammalian central nervous system (CNS) are primarily determined by ( S )‐glutamic acid (Glu) and 4‐aminobutyric acid (GABA), which hyperpolarizes neurons via multiple receptor subtypes. Glu can act as a neurotoxin and cause injury to neurons in neurological disorders, including reversal of Glu transporters. This article discusses functionality of GABA and glutamate receptor ligands, including their therapeutic potentials in CNS disorders.

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The Molecular Dynamic Simulation of Zolpidem Interaction with Gamma Aminobutyric Acid Type A Receptor

Chen

2007

J Chinese Chemical Soc

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Our goal was to generate the extracellular domain of gamma-aminobutyric acid type A receptor (GABA A receptor) by comparative modeling and to study the interaction of zolpidem with the GABA A receptor. The modeling strategy was verified to provide reasonable 3-dimensional coordinates. These coordinates helped to combine all the subunits well. The benzodiazepine (BZ) binding site was located in a binding pocket between the a1 and g2 subunits of the GABA A receptor. Zolpidem was selected to dock into the binding site. In our study, the residues of the binding pocket were suggested to be aHis129, aTyr187, aGly228, aThr234, aTyr237, gMet96, gPhe116, gSer130, gGly143, and gMet169. By the calculation of the docking module, the conformation of zolpidem docking in the BZ binding site was investigated. A hydrogen bond was found at gArg136 when zolpidem's conformation was in rank 2 of the docking score. The contracted binding pocket showed residues at aHis129, aTyr187, aGly228, aTyr237, gPhe116, and gMet169. Zolpidem docking in a contracted binding pocket might generate a hydrogen bond in aHis129.

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Comparative modeling of GABAA receptors: limits, insights, future developments

Cited by 148 publications

References 55 publications

Spontaneous Cross-link of Mutated α1 Subunits during GABAA Receptor Assembly

Spontaneous Cross-link of Mutated α1 Subunits during GABAA Receptor Assembly

GABAand Glutamate Receptor Ligands and their Therapeutic Potential inCNSDisorders

The Molecular Dynamic Simulation of Zolpidem Interaction with Gamma Aminobutyric Acid Type A Receptor

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