Rapid kinetics of agonist binding and permeability response analyzed in parallel on acetylcholine receptor rich membranes from Torpedo marmorata

Heidmann, Thiérry; Bernhardt, Julius; Neumann, Eberhard; Changeux, Jean Pierre

doi:10.1021/bi00292a029

Cited by 115 publications

(86 citation statements)

References 52 publications

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“…Taking the value of 0.5 #M as an average, this would suggest that half-maximal activation would occur at ~50 #M ACh. This value is in good agreement with actual measurements on BC3H-1 cells (Sine and Taylor, 1980;Brett et al, 1986) and on Torpedo membrane fragments (Neubig and Cohen, 1980;Heidmann et al, 1983), although it should be pointed out that the half-maximal concentration is liable to be voltage sensitive in cases where the response is voltage sensitive (as observed here for nearly all combinations).…”

Section: Each Is Roughly As Expectedsupporting

confidence: 92%

Equilibrium properties of mouse-Torpedo acetylcholine receptor hybrids expressed in Xenopus oocytes.

Yoshii

Mayne

et al. 1987

The Journal of General Physiology

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A B S T R A C T This study used messenger RNA encoding each subunit (a, fl, % and 6) of the nicotinic acetylcholine (ACh) receptor from mouse BC3H-1 cells and from Torpedo electric organ. The mRNA was synthesized in vitro by transcription with SP6 polymerase from cDNA clones. All 16 possible combinations that include one mRNA for each of a, fl, % and ~ were injected into oocytes. After allowing 2-8 d for translation and assembly, we assayed each oocyte for (a) receptor assembly, measured by the binding of [12sI]a-bungarotoxin to the oocyte surface, and (b) ACh-induced conductance, measured under voltage clamp at various membrane potentials. All combinations yielded detectable assembly (30-fold range among different combinations) and ACh-induced conductances (>l,000-fold range at 1 #M). On double-logarithmic coordinates, the dose-response relations all had a slope near 2 for low concentrations of ACh. Data were corrected for variations in efficiency of translation among identically injected oocytes by expressing ACh-induced conductance per femtomole of a-bungarotoxin-binding sites. Five combinations were tested for dtubocurarine inhibition by the dose-ratio method; the apparent dissociation constant ranged from 0.08 to 0.27 #M. Matched responses and geometric means are used for describing the effects of changing a particular subunit (mouse vs. Torpedo) while maintaining the identity of the other subunits. A dramatic subunit-specific effect is that of the fl subunit on voltage sensitivity of the response: gACh(--90 mV)/gAch(+30 mV) is always at least 1, but this ratio increases by an average of 3.5-fold if fl~a replaces fiT. Also, combinations including "YT or 6M usually produce greater receptor assembly than combinations including the homologous subunit from the other species. Finally, EACh is defined as the concentration of ACh inducing 1 #S/fmol at -60 mV; EACh is consistently lower for am. We conclude that receptor assembly, voltage sensitivity, and EACh are governed by different properties.

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Section: Each Is Roughly As Expectedsupporting

confidence: 92%

Equilibrium properties of mouse-Torpedo acetylcholine receptor hybrids expressed in Xenopus oocytes.

Yoshii

Mayne

et al. 1987

The Journal of General Physiology

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“…Moreover, accurate measurements made by Thierry Heidmann demonstrated that chlorpromazine binds to just one high-affinity site per 2α.β.γ.δ oligomer (95). The kinetics of access to this site increased 100-fold when chlorpromazine was rapidly mixed with acetylcholine under conditions expected to open the ion channel (96)(97)(98). We thus proposed that chlorpromazine binds to a site located within the ion channel, along the pseudosymmetry axis, that becomes accessible to chlorpromazine when the ion channel opens.…”

Section: Identification Of the Ion Channelmentioning

confidence: 99%

Allosteric Receptors: From Electric Organ to Cognition

Changeux

2010

Annu. Rev. Pharmacol. Toxicol.

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This autobiography covers the past 50 years beginning with the development of the concept of allosteric proteins and its application to pharmacological receptors. It continues with the identification of the nicotinic acetylcholine receptor, the discovery of its molecular organization, the structure of the acetylcholine-binding site and of the ion channel, and the demonstration of its allosteric transitions. The article then traces the origins of the concept of allosteric modulator and its consequences in pharmacology. It proceeds with the theory of selective stabilization of synapses and with experimental studies carried out on the contribution of the nicotinic receptor in the morphogenesis of the neuromuscular junction. The knowledge acquired with the nicotinic receptor is further exploited to reach higher levels of brain organization, and the contribution of nicotinic receptors to the action of nicotine on reward and cognition is explored, in particular, using a novel experimental strategy that combines nicotinic receptor genes knock-out and stereotaxic gene re-expression. Theoretical models of cognitive functions are proposed that link the molecular to the cognitive level. The report ends with a discussion on nicotinic receptors and the pharmacology of the future.

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“…In fact, some 20 years earlier Katz and Thesleff (1957) proposed a cyclic mechanism involving a desensitized state with increased agonist affinity relative to the resting state, and such a mechanism accounted for the observed time and concentration dependencies of the agonist-induced affinity increase (Weiland et al, 1977). Coincidence between the agonist-induced affinity increase and functional desensitization was demonstrated using dual measurements of agonist binding and activation (Sine and Taylor, 1979;Neubig et al, 1982;Heidmann et al, 1983). The emerging picture of the ligand binding site indicated a dynamic structure designed to shuttle among functional states to elicit the biological response following brief exposure to ACh and an attenuated response following prolonged exposure.…”

Section: Early Advances (1950s Through 1970s)mentioning

confidence: 99%

The nicotinic receptor ligand binding domain

2002

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ABSTRACT:The ligand binding domain (LBD) of the nicotinic acetylcholine receptor has served as a prototype for understanding molecular recognition in the family of neurotransmitter-gated ion channels. During the past fifty years, studies progressed from fundamental electrophysiological analyses of ACh-evoked ion flow, to biochemical purification of the receptor protein, pharmacological measurements of ligand binding, molecular cloning of receptor subunits, site-directed mutagenesis combined with functional analysis and recently, atomic structural determination. The emerging picture of the nicotinic receptor LBD is a specialized pocket of aromatic and hydrophobic residues formed at interfaces between protein subunits that changes conformation to convert agonist binding into gating of an intrinsic ion channel.

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Rapid kinetics of agonist binding and permeability response analyzed in parallel on acetylcholine receptor rich membranes from Torpedo marmorata

Cited by 115 publications

References 52 publications

Equilibrium properties of mouse-Torpedo acetylcholine receptor hybrids expressed in Xenopus oocytes.

Equilibrium properties of mouse-Torpedo acetylcholine receptor hybrids expressed in Xenopus oocytes.

Allosteric Receptors: From Electric Organ to Cognition

The nicotinic receptor ligand binding domain

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