Functional Consequences of the Loss of High Affinity Agonist Binding to γ-Aminobutyric Acid Type A Receptors

Newell, J. Glen; Dunn, Susan M. J.

doi:10.1074/jbc.m110312200

Cited by 14 publications

(11 citation statements)

References 26 publications

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“…This creates a use dependence for P2X 3 inhibition (Fig. 6 B) similar to that seen in other channels (Bartrup and Newberry, 1996;Newell and Dunn, 2002).…”

Section: Discussionmentioning

confidence: 86%

“…Nicotinic acetylcholine receptors (nAChR), GABA A receptors, 5-hydroxytryptamine receptors, and P2X 1 receptors are desensitized by concentrations of agonist that are lower than those required for channel activation (Katz and Theseleff, 1957;Bartrup and Newberry, 1996;Newell and Dunn, 2002;Paradiso and Steinbach, 2003). We found that 60 s of 0.5 nM ATP inhibited Ͼ50% of P2X 3 current after activation by high [agonist] (Fig.…”

Section: Discussionmentioning

confidence: 93%

“…It is assumed that the low-affinity activating site transitions to a high-affinity site during desensitization (Newell and Dunn, 2002). Therefore, both forms of the binding site may share similar properties.…”

Section: Discussionmentioning

confidence: 99%

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Use-Dependent Inhibition of P2X₃Receptors by Nanomolar Agonist

Pratt¹,

Brink²,

Bergson³

et al. 2005

J. Neurosci.

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P2X 3 receptors desensitize within 100 ms of channel activation, yet recovery from desensitization requires several minutes. The molecular basis for this slow rate of recovery is unknown. We designed experiments to test the hypothesis that this slow recovery is attributable to the high affinity (Ͻ1 nM) of desensitized P2X 3 receptors for agonist. We found that agonist binding to the desensitized state provided a mechanism for potent inhibition of P2X 3 current. Sustained applications of 0.5 nM ATP inhibited Ͼ50% of current to repetitive applications of P2X 3 agonist. Inhibition occurred at 1000-fold lower agonist concentrations than required for channel activation and showed strong use dependence. No inhibition occurred without previous activation and desensitization. Our data are consistent with a model whereby inhibition of P2X 3 by nanomolar [agonist] occurs by the rebinding of agonist to desensitized channels before recovery from desensitization. For several ATP analogs, the concentration required to inhibit P2X 3 current inversely correlated with the rate of recovery from desensitization. This indicates that the affinity of the desensitized state and recovery rate primarily depend on the rate of agonist unbinding. Consistent with this hypothesis, unbinding of [ 32 P]ATP from desensitized P2X 3 receptors mirrored the rate of recovery from desensitization. As expected, disruption of agonist binding by site-directed mutagenesis increased the IC 50 for inhibition and increased the rate of recovery.

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“…This creates a use dependence for P2X 3 inhibition (Fig. 6 B) similar to that seen in other channels (Bartrup and Newberry, 1996;Newell and Dunn, 2002).…”

Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 93%

See 1 more Smart Citation

Use-Dependent Inhibition of P2X₃Receptors by Nanomolar Agonist

Pratt¹,

Brink²,

Bergson³

et al. 2005

J. Neurosci.

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“…Such action may be expected if DCUK-OEt is shifting the GABA A receptor into a state more likely to be in an open channel configuration. The GABA A receptor has been shown to display two affinity states for agonists such as muscimol 46, 47 and the high affinity state of the GABA A receptor has been proposed to represent stabilization of the desensitized form of the receptor 48 . One can speculate that DCUK-OEt is increasing the proportion of receptors in a low affinity state at any particular concentration of agonist (muscimol).…”

Section: Discussionmentioning

confidence: 99%

Novel Molecule Exhibiting Selective Affinity for GABAA Receptor Subtypes

Borghese

Herman

Snell

et al. 2017

Sci Rep

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Aminoquinoline derivatives were evaluated against a panel of receptors/channels/transporters in radioligand binding experiments. One of these derivatives (DCUK-OEt) displayed micromolar affinity for brain γ-aminobutyric acid type A (GABAA) receptors. DCUK-OEt was shown to be a positive allosteric modulator (PAM) of GABA currents with α1β2γ2, α1β3γ2, α5β3γ2 and α1β3δ GABAA receptors, while having no significant PAM effect on αβ receptors or α1β1γ2, α1β2γ1, α4β3γ2 or α4β3δ receptors. DCUK-OEt modulation of α1β2γ2 GABAA receptors was not blocked by flumazenil. The subunit requirements for DCUK-OEt actions distinguished DCUK-OEt from other currently known modulators of GABA function (e.g., anesthetics, neurosteroids or ethanol). Simulated docking of DCUK-OEt at the GABAA receptor suggested that its binding site may be at the α + β- subunit interface. In slices of the central amygdala, DCUK-OEt acted primarily on extrasynaptic GABAA receptors containing the α1 subunit and generated increases in extrasynaptic “tonic” current with no significant effect on phasic responses to GABA. DCUK-OEt is a novel chemical structure acting as a PAM at particular GABAA receptors. Given that neurons in the central amygdala responding to DCUK-OEt were recently identified as relevant for alcohol dependence, DCUK-OEt should be further evaluated for the treatment of alcoholism.

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“…1). Additional evidence suggested involvement of the corresponding residue in the process of desensitization (Newell and Dunn 2002).…”

mentioning

confidence: 99%

On high‐ and low‐affinity agonist sites in GABA_A receptors

Baur

Sigel

2003

Journal of Neurochemistry

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GABA A receptors are activated via low-affinity binding sites for the agonists GABA or muscimol. Evidence has been provided that the amino acid residue a 1 F64 located at the b 2 (+)/a 1 (-) subunit interface forms part of this binding site. In radioactive ligand binding studies the agonist [ 3 H]muscimol has been found to interact with the receptor via a high-affinity binding site. This site has been interpreted as a conformational variant of the low-affinity site. Alternatively, the high-affinity binding site has been located to the a 1 (+)/b 2 (-) interface and the homologous residue to a 1 F64, b 2 Y62 has been proposed to constitute an important part of this site. Here we investigated the effect of the point mutation a 1 F64L and the homologous mutation b 2 Y62L on agonist and antagonist binding and functional properties in a 1 b 2 c 2 GABA A receptors. While the mutation in the a 1 subunit had drastic consequences on all studied properties, including desensitization, the mutation in the b 2 subunit had little consequence. Our observations are relevant for the relative location of high-and low-affinity agonist sites in GABA A receptors.

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Functional Consequences of the Loss of High Affinity Agonist Binding to γ-Aminobutyric Acid Type A Receptors

Cited by 14 publications

References 26 publications

Use-Dependent Inhibition of P2X₃Receptors by Nanomolar Agonist

Use-Dependent Inhibition of P2X₃Receptors by Nanomolar Agonist

Novel Molecule Exhibiting Selective Affinity for GABAA Receptor Subtypes

On high‐ and low‐affinity agonist sites in GABA_A receptors

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Functional Consequences of the Loss of High Affinity Agonist Binding to γ-Aminobutyric Acid Type A Receptors

Cited by 14 publications

References 26 publications

Use-Dependent Inhibition of P2X3Receptors by Nanomolar Agonist

Use-Dependent Inhibition of P2X3Receptors by Nanomolar Agonist

Novel Molecule Exhibiting Selective Affinity for GABAA Receptor Subtypes

On high‐ and low‐affinity agonist sites in GABAA receptors

Contact Info

Product

Resources

About

Use-Dependent Inhibition of P2X₃Receptors by Nanomolar Agonist

Use-Dependent Inhibition of P2X₃Receptors by Nanomolar Agonist

On high‐ and low‐affinity agonist sites in GABA_A receptors