Allosteric modulation of muscarinic acetylcholine receptors

Tuček, Stanislav; Proška, Jan

doi:10.1016/s0165-6147(00)89023-9

Cited by 149 publications

(87 citation statements)

References 29 publications

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“…A large number of allosteric modulators selectively affect binding of the competitive ligands to M 2 receptors (Tucek and Proska, 1995). Several lines of evidence suggest that muscarinic allosteric ligands (e.g., gallamine and alcuronium) bind to the extracellular domain of muscarinic receptors (Jakubík and Tucek, 1994;Leppik et al, 1994;Proska and Tucek, 1994), and that amino acid residues in the second and third extracellular loops are important for this mode of binding (Leppik et al, 1994;Matsui et al, 1995;Gnagey et al, 1999;Krejcí and Tucek, 2001;Jakubík et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Molecular Mechanisms of Methoctramine Binding and Selectivity at Muscarinic Acetylcholine Receptors

et al. 2014

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Methoctramine (N,-methyl]hexyl]-1,8-octane] diamine) is an M 2 -selective competitive antagonist of muscarinic acetylcholine receptors and exhibits allosteric properties at high concentrations. To reveal the molecular mechanisms of methoctramine binding and selectivity we took advantage of reciprocal mutations of the M 2 and M 3 receptors in the second and third extracellular loops that are involved in the binding of allosteric ligands. To this end we performed measurements of kinetics of the radiolabeled antagonists N-methylscopolamine (NMS) in the presence of methoctramine and its precursors, fluorescence energy transfer between green fluorescent protein-fused receptors and an Alexa-555-conjugated precursor of methoctramine, and simulation of molecular dynamics of methoctramine association with the receptor. We confirm the hypothesis that methoctramine high-affinity binding to the M 2 receptors involves simultaneous interaction with both the orthosteric binding site and the allosteric binding site located between the second and third extracellular loops. Methoctramine can bind solely with low affinity to the allosteric binding site on the extracellular domain of NMSoccupied M 2 receptors by interacting primarily with glutamate 175 in the second extracellular loop. In this mode, methoctramine physically prevents dissociation of NMS from the orthosteric binding site. Our results also demonstrate that lysine 523 in the third extracellular loop of the M 3 receptors forms a hydrogen bond with glutamate 219 of the second extracellular loop that hinders methoctramine binding to the allosteric site at this receptor subtype. Impaired interaction with the allosteric binding site manifests as low-affinity binding of methoctramine at the M 3 receptor.

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Section: Introductionmentioning

confidence: 99%

Molecular Mechanisms of Methoctramine Binding and Selectivity at Muscarinic Acetylcholine Receptors

et al. 2014

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“…The typical 2 allosteric site is thought to be located on the extracellular lip of the receptor (Ellis et al, 1993;Leppik et al, 1994;Tuček and Proska, 1995). Ligands such as gallamine and obidoxime have been shown to bind to this secondary binding site (Clark and Mitchelson, 1976;Trankle and Mohr, 1997), and this site is estimated to be in close proximity to the orthosteric site (Tuček and Proska, 1995). Based upon this estimation, we believed that a priori design of novel multivalent ligands, designed to span and bind to both sites simultaneously, should be possible.…”

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confidence: 99%

A Novel Multivalent Ligand That Bridges the Allosteric and Orthosteric Binding Sites of the M₂ Muscarinic Receptor

et al. 2007

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THRX-160209 is a potent antagonist at the M 2 muscarinic acetylcholine (ACh) receptor subtype that was designed using a multivalent strategy, simultaneously targeting the orthosteric site and a nearby site known to bind allosteric ligands. In this report, we describe three characteristics of THRX-160209 binding that are consistent with a multivalent interaction: 1) an apparent affinity of the multivalent ligand for the M 2 receptor subtype (apparent pK I ϭ 9.51 Ϯ 0.22) that was several orders of magnitude greater than its two monovalent components (apparent pK I values Ͻ 6.0), 2) specificity of THRX-160209 for the M 2 receptor subtype compared with the closely related M 4 (apparent pK I ϭ 8.78 Ϯ 0.24) and M 1 , M 3 , and M 5 receptors (apparent pK I values Յ 8.0), and 3) acceleration (Ͼ10-fold) of the dissociation rate of tritium-labeled THRX-160209 from M 2 receptors by competing monovalent ligands that are known to interact with either the orthosteric site (e.g., atropine) or a well characterized allosteric site (e.g., obidoxime) on the receptor. In complementary kinetic studies assessing allosteric modulation of the receptor, unlabeled THRX-160209 retarded dissociation of [3 H]N-methyl scopolamine (NMS). The effects of THRX-160209 on retardation of [ 3 H]NMS dissociation were competitively inhibited by obidoxime, suggesting that obidoxime and THRX-160209 bind to an overlapping region coincident with other typical muscarinic allosteric agents, such as 3-methyl-5-W84) and gallamine. Taken together, these data are consistent with the hypothesis that THRX-160209 binds in a multivalent manner to the M 2 receptor, simultaneously occupying the orthosteric site and a spatially distinct allosteric site.The muscarinic receptor family consists of five subtypes that are found in smooth and cardiac muscle, epithelial and endothelial cells, secretory cells, neurons, and inflammatory cells (Caulfield, 1993;Racke and Matthiesen, 2004). These receptors represent attractive targets for drug design in a variety of therapeutic areas, including overactive bladder, chronic obstructive pulmonary disease, and Parkinson's disease (Eglen et al., 2001;Katzenschlager et al., 2003;Barnes, 2004;Hegde et al., 2004). However, most currently marketed, muscarinic receptor-targeted therapies exhibit significant side effects, some of which are due to potent drug interactions at undesirable muscarinic receptor subtypes outside the intended organ system. High sequence homology within the orthosteric site, across the five receptor subtypes, makes the synthesis of tissue-specific or subtype-specific drugs challenging (Hulme et al., 1990). A drug with specificity for a given subtype or tissue is predicted to have increased efficacy but decreased side effects relative to a drug with equal affinity for all subtypes (Gainetdinov and Caron, 1999).Muscarinic receptors are known to be subject to modulation by ligands that do not bind to the ACh binding pocket (the "orthosteric site") (Ellis et al., 1991). Targeting these "secondary" or "allosteri...

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“…The best characterized examples are gallamine and alcuronium, which allosterically modulate muscarinic acetylcholine receptors (Stockton et al, 1983;Proska & Tucek, 1994;Tucek & Proska, 1995). Allosteric modulators may provide therapeutic advantages compared with conventional competitive ligands .…”

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confidence: 99%

Regulation of human D₁, D_2(long), D_2(short), D₃and D₄dopamine receptors by amiloride and amiloride analogues

Hoare

Coldwell

Armstrong

et al. 2000

British J Pharmacology

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, Reading RG6 6AJ1 The modulatory e ects of the allosteric e ectors methylisobutylamiloride (MIA), benzamil and amiloride have been examined at human D 1 , D 2 , D 3 and D 4 dopamine receptors. The subtype selectivity and the mechanism of action of this allosteric regulation was examined. 2 In radioligand dissociation experiments each modulator accelerated dissociation from all four receptor subtypes indicating allosteric regulation. MIA displayed selectivity for the D 3 subtype for acceleration of radioligand dissociation. 3 In equilibrium binding (pseudo-competition) experiments the three compounds inhibited radioligand binding at the four receptor subtypes. Inhibition curves for D 1 , D 2(short) , D 2(long) and D 3 receptors were described by Hill coe cients exceeding unity and data were ®tted best by a model that assumes binding of modulator to both the primary and allosteric binding sites of the receptor (the allosteric/competitive model). 4 At the D 4 subtype, Hill coe cients of unity described the binding data for amiloride and benzamil, consistent with competitive inhibition. The Hill coe cient for MIA at the D 4 subtype was less than unity and data could be ®tted well by the allosteric/competitive model, but it was not possible to de®ne unambiguously the modulatory mechanism. For this e ect a better de®nition of the mechanism could be obtained by simultaneous analysis of data obtained in the presence of a range of concentrations of a purely competitive ligand. 5 MIA reduced the potency with which dopamine stimulated [ 35 S]-GTPgS binding at the D 2 receptor. The e ects of MIA could be described by the allosteric/competitive model with e ects of MIA to inhibit the binding of dopamine but not its ability to induce a response.

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Allosteric modulation of muscarinic acetylcholine receptors

Cited by 149 publications

References 29 publications

Molecular Mechanisms of Methoctramine Binding and Selectivity at Muscarinic Acetylcholine Receptors

Molecular Mechanisms of Methoctramine Binding and Selectivity at Muscarinic Acetylcholine Receptors

A Novel Multivalent Ligand That Bridges the Allosteric and Orthosteric Binding Sites of the M₂ Muscarinic Receptor

Regulation of human D₁, D_2(long), D_2(short), D₃and D₄dopamine receptors by amiloride and amiloride analogues

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Allosteric modulation of muscarinic acetylcholine receptors

Cited by 149 publications

References 29 publications

Molecular Mechanisms of Methoctramine Binding and Selectivity at Muscarinic Acetylcholine Receptors

Molecular Mechanisms of Methoctramine Binding and Selectivity at Muscarinic Acetylcholine Receptors

A Novel Multivalent Ligand That Bridges the Allosteric and Orthosteric Binding Sites of the M2 Muscarinic Receptor

Regulation of human D1, D2(long), D2(short), D3and D4dopamine receptors by amiloride and amiloride analogues

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A Novel Multivalent Ligand That Bridges the Allosteric and Orthosteric Binding Sites of the M₂ Muscarinic Receptor

Regulation of human D₁, D_2(long), D_2(short), D₃and D₄dopamine receptors by amiloride and amiloride analogues