Abstract
Cys-loop receptors mediate rapid transmission throughout the nervous system by converting a chemical signal into an electric one. They are pentameric proteins with an extracellular domain that carries the transmitter binding sites and a transmembrane region that forms the ion pore. Their essential function is to couple the binding of the agonist at the extracellular domain to the opening of the ion pore. How the structural changes elicited by agonist binding are propagated through a distance of 50 Å to the gate is therefore central for the understanding of the receptor function. A step forward toward the identification of the structures involved in gating has been given by the recently elucidated high-resolution structures of Cys-loop receptors and related proteins. The extracellular–transmembrane interface has attracted attention because it is a structural transition zone where β-sheets from the extracellular domain merge with α-helices from the transmembrane domain. Within this zone, several regions form a network that relays structural changes from the binding site toward the pore, and therefore, this interface controls the beginning and duration of a synaptic response. In this review, the most recent findings on residues and pairwise interactions underlying channel gating are discussed, the main focus being on the extracellular–transmembrane interface.
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References
Le Novere N, Changeux JP (2001) The Ligand Gated Ion Channel database: an example of a sequence database in neuroscience. Philos Trans R Soc Lond B Biol Sci 356:1121–1130
Lester HA, Dibas MI, Dahan DS, Leite JF, Dougherty DA (2004) Cys-loop receptors: new twists and turns. Trends Neurosci 27:329–336
Sine SM, Engel AG (2006) Recent advances in Cys-loop receptor structure and function. Nature 440:448–455
Collingridge GL, Olsen RW, Peters J, Spedding M (2009) A nomenclature for ligand-gated ion channels. Neuropharmacology 56:2–5
Kalamida D, Poulas K, Avramopoulou V, Fostieri E, Lagoumintzis G, Lazaridis K, Sideri A, Zouridakis M, Tzartos SJ (2007) Muscle and neuronal nicotinic acetylcholine receptors. Structure, function and pathogenicity. FEBS J 274:3799–3845
Beg AA, Jorgensen EM (2003) EXP-1 is an excitatory GABA-gated cation channel. Nat Neurosci 6:1145–1152
Putrenko I, Zakikhani M, Dent JA (2005) A family of acetylcholine-gated chloride channel subunits in Caenorhabditis elegans. J Biol Chem 280:6392–6398
Zheng Y, Hirschberg B, Yuan J, Wang AP, Hunt DC, Ludmerer SW, Schmatz DM, Cully DF (2002) Identification of two novel Drosophila melanogaster histamine-gated chloride channel subunits expressed in the eye. J Biol Chem 277:2000–2005
Vassilatis DK, Elliston KO, Paress PS, Hamelin M, Arena JP, Schaeffer JM, Van der Ploeg LH, Cully DF (1997) Evolutionary relationship of the ligand-gated ion channels and the avermectin-sensitive, glutamate-gated chloride channels. J Mol Evol 44:501–508
Wolstenholme AJ, Rogers AT (2005) Glutamate-gated chloride channels and the mode of action of the avermectin/milbemycin anthelmintics. Parasitology 131:85–95
Jones AK, Sattelle DB (2008) The cys-loop ligand-gated ion channel gene superfamily of the nematode, Caenorhabditis elegans. Invert Neurosci 8:41–47
Ringstad N, Abe N, Horvitz HR (2009) Ligand-gated chloride channels are receptors for biogenic amines in C. elegans. Science 325:96–100
Bernard C (1857) Leçons sur Les effets des substances toxiques et Medicamenteuses. Bailliere, Paris
Le Novere N, Changeux JP (1995) Molecular evolution of the nicotinic acetylcholine receptor subunit family: an example of multigene family in excitable cells. J Mol Evol 40:155–172
Arias HR, Bhumireddy P, Bouzat C (2006) Molecular mechanisms and binding site locations for noncompetitive antagonists of nicotinic acetylcholine receptors. Int J Biochem Cell Biol 38:1254–1276
Jones AK, Sattelle DB (2003) Functional genomics of the nicotinic acetylcholine receptor gene family of the nematode, Caenorhabditis elegans. Bioessays 26:39–49
De Rosa MJ, del Esandi MC, Garelli A, Rayes D, Bouzat C (2005) Relationship between alpha7 nAChR and apoptosis in human lymphocytes. J Neuroimmunol 160:154–161
Maus AD, Pereira EF, Karachunski PI, Horton RM, Navaneetham D, Macklin K, Cortes WS, Albuquerque EX, Conti-Fine BM (1998) Human and rodent bronchial epithelial cells express functional nicotinic acetylcholine receptors. Mol Pharmacol 54:779–788
Macklin KD, Maus AD, Pereira EF, Albuquerque EX, Conti-Fine BM (1998) Human vascular endothelial cells express functional nicotinic acetylcholine receptors. J Pharmacol Exp Ther 287:435–439
Conti-Fine BM, Navaneetham D, Lei S, Maus AD (2000) Neuronal nicotinic receptors in non-neuronal cells: new mediators of tobacco toxicity? Eur J Pharmacol 393:279–294
Wessler I, Kilbinger H, Bittinger F, Unger R, Kirkpatrick CJ (2003) The non-neuronal cholinergic system in humans: expression, function and pathophysiology. Life Sci 72:2055–2061
Hoyer D, Hannon JP, Martin GR (2002) Molecular, pharmacological and functional diversity of recombinant 5-HT receptors. Pharmacol Biochem Behav 71:533–554
Yang HS, Yun Kim SY, Choi SJ, Kim K-J, Kim ON, Lee SB, Sung K-W (2003) Effect of 5-hydroxyindole on ethanol potentiation of 5-hydroxytryptamine 5-HT3 receptor-activated ion current in NCB-20 neuroblastoma cells. Neurosci Lett 338:72–76
Davies PA, Pistis M, Hanna MC, Peters JA, Lambert JJ, Hales TG, Kirkness EF (1999) The 5-HT3B subunit is a major determinant of serotonin-receptor function. Nature 397:359–363
Dubin AE, Huvar R, D'Andrea MR, Pyati J, Zhu JY, Joy KC, Wilson SJ, Galindo JE, Glass CA, Luo L, Jackson MR, Lovenberg TW, Erlander MG (1999) The pharmacological and functional characteristics of the serotonin 5-HT3A receptor are specifically modified by a 5-HT3B receptor subunit. J Biol Chem 274:30799–30810
Niesler B, Kapeller FB, Rappold GA (2003) Cloning, physical mapping and expression analysis of the human 5-HT3 serotonin receptor-like genes HTR3C, HTR3D and HTR3E. Gene 310:101–111
Niesler B, Walstab J, Combrink S, Möller D, Kapeller J, Rietdorf J, Bönisch H, Göthert M, Rappold G, Brüss M (2007) Characterization of the novel human serotonin receptor subunits 5-HT3C, 5-HT3D, and 5-HT3E. Mol Pharmacol 72:8–17
Jensen AA, Davies PA, Bräuner-Osborne H, Krzywkowski K (2008) 3B but which 3B? and that's just one of the questions: the heterogeneity of human 5-HT3 receptors. Trends Pharmacol Sci 29:437–444
Holbrook JD, Gill CH, Zebda N, Spencer JP, Leyland R, Rance KH, Trinh H, Balmer G, Kelly FM, Yusaf SP, Courtenay N, Luck J, Rhodes A, Modha S, Moore SE, Sanger GJ, Gunthorpe MJ (2009) Characterisation of 5-HT3C, 5-HT3D and 5-HT3E receptor subunits: evolution, distribution and function. J Neurochem 108:384–396
Hussy N, Lukas W, Jones KA (1994) Functional properties of a cloned 5-hydroxytryptamine ionotropic receptor subunit: comparison with native mouse receptors. J Physiol 481:311–323
Maricq AV, Peterson AS, Brake AJ, Myers RM, Julius D (1991) Primary structure and functional expression of the 5HT3 receptor, a serotonin-gated ion channel. Science 254:432–437
Akk G, Covey DF, Evers AS, Steinbach JH, Zorumski CF, Mennerick S (2007) Mechanisms of neurosteroid interactions with GABAA receptors. Pharmacol Ther 116:35–57
Olsen RW, Sieghart W (2009) GABAA receptors: subtypes provide diversity of function and pharmacology. Neuropharmacology 56:141–148
Chang Y, Weiss DS (2002) Site-specific fluorescence reveals distinct structural changes with GABA receptor activation and antagonism. Nat Neurosci 5:1163–1168
Hanson SM, Czajkowski C (2008) Structural mechanisms underlying benzodiazepine modulation of the GABAA receptor. J Neurosci 28:3490–3499
Connolly CN, Wafford KA (2004) Molecular structure in ligand-gated ion channel function. Biochemical Soc Transactions 32:529–534
Albuquerque EX, Pereira EF, Alkondon M, Rogers SW (2009) Mammalian nicotinic acetylcholine receptors: from structure to function. Physiol Rev 89:73–120
Unwin N (2005) Refined structure of the nicotinic acetylcholine receptor at 4 Å resolution. J Mol Biol 346:967–989
Dellisanti CD, Yao Y, Stroud JC, Wang ZZ, Chen L (2007) Crystal structure of the extracellular domain of nAChR alpha1 bound to alpha-bungarotoxin at 1.94 Å resolution. Nat Neurosci 10:953–962
Brejc K, van Dijk WJ, Klaassen RV, Schuurmans M, van Der Oost J, Smit AB, Sixma TK (2001) Crystal structure of an ACh-binding protein reveals the ligand-binding domain of nicotinic receptors. Nature 411:269–276
Smit AB, Syed NI, Schaap D, van Minnen J, Klumperman J, Kits KS, Lodder H, van der Schors RC, van Elk R, Sorgedrager B, Brejc K, Sixma TK, Geraerts WP (2001) A glia-derived acetylcholine-binding protein that modulates synaptic transmission. Nature 411:261–268
Hansen SB, Sulzenbacher G, Huxford T, Marchot P, Taylor P, Bourne Y (2005) Structures of Aplysia AChBP complexes with nicotinic agonists and antagonists reveal distinctive binding interfaces and conformations. EMBO J 24:3635–3646
Celie PH, Klaassen RV, van Rossum-Fikkert SE, van Elk R, van Nierop P, Smit AB, Sixma TK (2005) Crystal structure of acetylcholine-binding protein from Bulinus truncatus reveals the conserved structural scaffold and sites of variation in nicotinic acetylcholine receptors. J Biol Chem 280:26457–26466
Hilf RJ, Dutzler R (2008) X-ray structure of a prokaryotic pentameric ligand-gated ion channel. Nature 452:375–379
Hilf RJ, Dutzler R (2009) Structure of a potentially open state of a proton-activated pentameric ligand-gated ion channel. Nature 457:115–118
Bocquet N, Nury H, Baaden M, Le Poupon C, Changeux JP, Delarue M, Corringer PJ (2009) X-ray structure of a pentameric ligand-gated ion channel in an apparently open conformation. Nature 457:111–114
Sine SM (2002) The nicotinic receptor ligand binding domain. J Neurobiol 53:431–446
Cromer BA, Morton CJ, Parker MW (2002) Anxiety over GABAA receptor structure relieved by AChBP. Trends Biochem Sci 27:280–287
Reeves DC, Sayed MF, Chau PL, Price KL, Lummis SC (2003) Prediction of 5-HT3 receptor agonist-binding residues using homology modeling. Biophys J 84:2338–2344
Absalom NL, Lewis TM, Kaplan W, Pierce KD, Schofield PR (2003) Role of charged residues in coupling ligand binding and channel activation in the extracellular domain of the glycine receptor. J Biol Chem 278:50151–50157
Changeux J, Edelstein SJ (2001) Allosteric mechanisms in normal and pathological nicotinic acetylcholine receptors. Curr Opin Neurobiol 11:369–377
Changeux JP, Taly A (2008) Nicotinic receptors, allosteric proteins and medicine. Trends Mol Med 14:93–102
Ortells MO, Lunt GG (1995) Evolutionary history of the ligand-gated ion-channel superfamily of receptors. Trends Neurosci 18:121–127
Le Novère N, Corringer PJ, Changeux JP (2002) The diversity of subunit composition in nAChRs: evolutionary origins, physiologic and pharmacologic consequences. J Neurobiol 53:447–456
Tasneem A, Iyer LM, Jakobsson E, Aravind L (2005) Identification of the prokaryotic ligand-gated ion channels and their implications for the mechanisms and origins of animal Cys-loop ion channels. Genome Biol 6:R4
Seo S, Henry JT, Lewis AH, Wang N, Levandoski MM (2009) The positive allosteric modulator morantel binds at noncanonical subunit interfaces of neuronal nicotinic acetylcholine receptors. J Neurosci 29:8734–8742
Solt K, Ruesch D, Forman SA, Davies PA, Raines DE (2007) Differential effects of serotonin and dopamine on human 5-HT3A receptor kinetics: interpretation within an allosteric kinetic model. J Neurosci 27:13151–13160
Corradi J, Gumilar F, Bouzat C (2009) Single-channel kinetic analysis for activation and desensitization of homomeric 5-HT3A receptors. Biophys J 97:1335–1345
Rayes D, De Rosa MJ, Sine SM, Bouzat C (2009) Number and locations of agonist binding sites required to activate homomeric Cys-loop receptors. J Neurosci 29:6022–6032
Jones IW, Wonnacott S (2004) Precise localization of alpha7 nicotinic acetylcholine receptors on glutamatergic axon terminals in the rat ventral tegmental area. J Neurosci 24:11244–11252
Miyazawa A, Fujiyoshi Y, Unwin N (2003) Structure and gating mechanism of the acetylcholine receptor pore. Nature 423:949–955
Villarroel A, Sakmann B (1992) Threonine in the selectivity filter of the acetylcholine receptor channel. Biophys J 62:196–205
Burden SJ, Desalma RL, Gottesman GS (1983) Crosslinking of proteins in acetycholine receptor-rich membranes: association between the β-subunit and the 43 kd subsynaptic protein. Cell 35:687–692
Froehner SC (1991) The submembrane machinery for nicotinic acetylcholine receptor clustering. J Cell Biol 114:1–7
Passafaro M, Sheng M (1999) Synaptogenesis: the MAP location of GABA receptors. Curr Biol 9:261–263
Feng G, Steinbach JH, Sanes JR (1998) Rapsyn clusters neuronal acetylcholine receptors but is inessential for formation of an interneuronal cholinergic synapse. J Neurosci 18:4166–4176
Conroy WG, Berg DK (1999) Rapsyn variants in ciliary ganglia and their possible effects on clustering of nicotinic receptors. J Neurochem 73:1399–1408
Bruneau E, Akaaboune M (2007) The dynamics of the rapsyn scaffolding protein at individual acetylcholine receptor clusters. J Biol Chem 282:9932–9940
Bouzat C, Bren N, Sine SM (1994) Structural basis of the different gating kinetics of fetal and adult nicotinic acetylcholine receptors. Neuron 13:1395–1402
Wang HL, Ohno K, Milone M, Brengman JM, Evoli A, Batocchi AP, Middleton LT, Christodoulou K, Engel AG, Sine SM (2000) Fundamental gating mechanism of nicotinic receptor channel revealed by mutation causing a congenital myasthenic syndrome. J Gen Physiol 116:449–462
Kelley SP, Dunlop JI, Kirkness EF, Lambert JJ, Peters JA (2003) A cytoplasmic region determines single-channel conductance in 5-HT3 receptors. Nature 424:321–324
Rayes D, Spitzmaul G, Sine SM, Bouzat C (2005) Single-channel kinetic analysis of chimeric alpha7–5HT3A receptors. Mol Pharmacol 68:1475–1483
Bouzat C, Bartos M, Corradi J, Sine SM (2008) The interface between extracellular and transmembrane domains of homomeric Cys-loop receptors governs open-channel lifetime and rate of desensitization. J Neurosci 28:7808–7819
Huganir RL, Delcour AH, Greengard P, Hess GP (1986) Phosphorylation of the nicotinic acetylcholine receptor regulates its rate of desensitization. Nature 321:774–776
Swope SL, Qu Z, Huganir RL (1995) Phosphorylation of the nicotinic acetylcholine receptor by protein tyrosine kinases. Ann NY Acad Sci 757:197–214
Fenster CP, Beckman ML, Parker JC, Sheffield EB, Whitworth TL, Quick MW, Lester RA (1999) Regulation of α4β2 nicotinic receptor desensitization by calcium and protein kinase C. Mol Pharmacol 55:432–443
Pacheco MA, Pastoor TE, Wecker L (2003) Phosphorylation of the α4 subunit of human α4β2 nicotinic receptors: role of cAMP-dependent protein kinase (PKA) and protein kinase C (PKC). Brain Res Mol Brain Res 114:65–72
Wang K, Hackett JT, Cox ME, Van Hoek M, Lindstrom JM, Parsons SJ (2004) Regulation of the neuronal nicotinic acetylcholine receptor by SRC family tyrosine kinases. J Biol Chem 279:8779–8786
Cho CH, Song W, Leitzell K, Teo E, Meleth AD, Quick MW, Lester RA (2005) Rapid upregulation of α7 nicotinic acetylcholine receptors by tyrosine dephosphorylation. J Neurosci 25:3712–3723
Wiesner A, Fuhrer C (2006) Regulation of nicotinic acetylcholine receptors by tyrosine kinases in the peripheral and central nervous system: same players, different roles. Cell Mol Life Sci 63:2818–2828
Bocquet N, Prado de Carvalho L, Cartaud J, Neyton J, Le Poupon C, Taly A, Grutter T, Changeux JP, Corringer PJ (2007) A prokaryotic proton-gated ion channel from the nicotinic acetylcholine receptor family. Nature 445:116–119
Del Castillo L, Katz B (1957) A study of curare action with an electrical micromethod. Proc R Soc Lond B Biol Sci 146:339–356
Monod J, Wyman J, Changeux JP (1965) On the nature of the allosteric proteins: a plausible model. J Mol Biol 12:88–118
Changeux JP, Edelstein SJ (2005) Allosteric mechanisms of signal transduction. Science 308:1424–1428
Edelstein SJ, Changeux JP (1996) Allosteric proteins after thirty years: the binding and state functions of the neuronal alpha 7 nicotinic acetylcholine receptors. Experientia 52:1083–1090
Neher E, Sakmann B (1976) Single-channel currents recorded from membrane of denervated frog muscle fibres. Nature 260:799–802
Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch 391:85–100
Colquhoun D (2006) Agonist-activated ion channels. Br J Pharmacol 147:17–26
Colquhoun D (2006) The quantitative analysis of drug-receptor interactions: a short history. Trends Pharmacol Sci 27:149–157
Colquhoun D, Hawkes AG, Srodzinski K (1996) Joint distributions of apparent open times and shut times of single ion channels and the maximum likelihood fitting of mechanisms. Philos Trans R Soc Lond A 354:2555–2590
Qin F, Auerbach A, Sachs F (1996) Estimating single-channel kinetic parameters from idealized patch-clamp data containing missed events. Biophys J 70:264–280
Sine SM, Ohno K, Bouzat C, Auerbach A, Milone M, Pruitt JN, Engel AG (1995) Mutation of the acetylcholine receptor alpha subunit causes a slow-channel myasthenic syndrome by enhancing agonist binding affinity. Neuron 15:229–239
Salamone FN, Zhou M, Auerbach A (1999) A re-examination of adult mouse nicotinic acetylcholine receptor channel activation kinetics. J Physiol 516:315–330
Bouzat C, Barrantes F, Sine S (2000) Nicotinic receptor fourth transmembrane domain: hydrogen bonding by conserved threonine contributes to channel gating kinetics. J Gen Physiol 115:663–672
Burzomato V, Beato M, Groot-Kormelink PJ, Colquhoun D, Sivilotti LG (2004) Single-channel behavior of heteromeric alpha1beta glycine receptors: an attempt to detect a conformational change before the channel opens. J Neurosci 24:10924–10940
Akk G, Bracamontes J, Steinbach JH (2004) Activation of GABA(A) receptors containing the alpha4 subunit by GABA and pentobarbital. J Physiol 556:387–399
Lape R, Colquhoun D, Sivilotti LG (2008) On the nature of partial agonism in the nicotinic receptor superfamily. Nature 454:722–727
Mukhtasimova N, Lee WY, Wang HL, Sine SM (2009) Detection and trapping of intermediate states priming nicotinic receptor channel opening. Nature 459:451–454
Liu Y, Dilger JP (1991) Opening rate of acetylcholine receptor channels. Biophys J 60:424–432
Grosman C, Salamone FN, Sine SM, Auerbach A (2000) The extracellular linker of muscle acetylcholine receptor channels is a gating control element. J Gen Physiol 116:327–340
Purohit P, Auerbach A (2007) Acetylcholine receptor gating at extracellular transmembrane domain interface: the “pre-M1” linker. J Gen Physiol 130:559–568
Zhou Y, Pearson JE, Auerbach A (2005) Phi-value analysis of a linear, sequential reaction mechanism: theory and application to ion channel gating. Biophys J 89:3680–3685
Auerbach A (2007) How to turn the reaction coordinate into time. J Gen Physiol 130:543–546
Purohit P, Mitra A, Auerbach A (2007) A stepwise mechanism for acetylcholine receptor channel gating. Nature 446:930–933
Purohit P, Auerbach A (2009) Unliganded gating of acetylcholine receptor channels. Proc Natl Acad Sci USA 106:115–120
Taly A, Delarue M, Grutter T, Nilges M, Le Novère N, Corringer PJ, Changeux JP (2005) Normal mode analysis suggests a quaternary twist model for the nicotinic receptor gating mechanism. Biophys J 88:3954–3965
Taly A, Corringer PJ, Grutter T, Prado de Carvalho L, Karplus M, Changeux JP (2006) Implications of the quaternary twist allosteric model for the physiology and pathology of nicotinic acetylcholine receptors. Proc Natl Acad Sci USA 103:16965–16970
Taly A (2007) Opened by a twist: a gating mechanism for the nicotinic acetylcholine receptor. Eur Biophys J 36:911–918
Cheng X, Lu B, Grant B, Law RJ, McCammon JA (2006) Channel opening motion of alpha7 nicotinic acetylcholine receptor as suggested by normal mode analysis. J Mol Biol 355:310–324
Liu X, Xu Y, Li H, Wang X, Jiang H, Barrantes FJ (2008) Mechanics of channel gating of the nicotinic acetylcholine receptor. PLoS Comput Biol 4:100–110
Celie PH, van Rossum-Fikkert SE, van Dijk WJ, Brejc K, Smit AB, Sixma TK (2004) Nicotine and carbamylcholine binding to nicotinic acetylcholine receptors as studied in AChBP crystal structures. Neuron 41:907–914
Dougherty DA (2007) Cation–pi interactions involving aromatic amino acids. J Nutr 137:1504S–1508S discussion 1516S–1517S
Xiu X, Puskar NL, Shanata JA, Lester HA, Dougherty DA (2009) Nicotine binding to brain receptors requires a strong cation–pi interaction. Nature 458:534–537
Ulens C, Hogg RC, Celie PH, Bertrand D, Tsetlin V, Smit AB, Sixma TK (2006) Structural determinants of selective alpha-conotoxin binding to a nicotinic acetylcholine receptor homolog AChBP. Proc Natl Acad Sci USA 103:3615–3620
Dutertre S, Lewis RJ (2006) Toxin insights into nicotinic acetylcholine receptors. Biochem Pharmacol 72:661–670
Gao F, Bren N, Burghardt TP, Hansen S, Henchman RH, Taylor P, McCammon JA, Sine SM (2005) Agonist-mediated conformational changes in acetylcholine-binding protein revealed by simulation and intrinsic tryptophan fluorescence. J Biol Chem 280:8443–8451
Law RJ, Henchman RH, Mc Cammon JA (2005) A gating mechanism proposed from a simulation of a human alpha7 nicotinic acetylcholine receptor. Proc Natl Acad Sci USA 102:6813–6818
Mukhtasimova N, Free C, Sine SM (2005) Initial coupling of binding to gating mediated by conserved residues in the muscle nicotinic receptor. J Gen Physiol 126:23–39
Venkatachalan SP, Czajkowski C (2008) A conserved salt bridge critical for GABA(A) receptor function and loop C dynamics. Proc Natl Acad Sci USA 105:13604–13609
Mukhtasimova N, Sine SM (2007) An intersubunit trigger of channel gating in the muscle nicotinic receptor. J Neurosci 27:4110–4119
Wang HL, Toghraee R, Papke D, Cheng XL, McCammon JA, Ravaioli U, Sine SM (2009) Single-channel current through nicotinic receptor produced by closure of binding site C-loop. Biophys J 96:3582–3590
Akk G (2002) Contributions of the non-alpha subunit residues (loop D) to agonist binding and channel gating in the muscle nicotinic acetylcholine receptor. J Physiol 544:695–705
Gay EA, Yakel JL (2007) Gating of nicotinic ACh receptors; new insights into structural transitions triggered by agonist binding that induce channel opening. J Physiol 584:727–733
Bartos M, Price KL, Lummis SC, Bouzat C (2009) Glutamine 57 at the complementary binding site face is a key determinant of morantel selectivity for α7 nicotinic receptors. J Biol Chem 284:21478–21487
Rayes D, De Rosa MJ, Bartos M, Bouzat C (2004) Molecular basis of the differential sensitivity of nematode and mammalian muscle to the anthelmintic agent levamisole. J Biol Chem 279:36372–36381
Grutter T, Prado de Carvalho L, Le Novère N, Corringer PJ, Edelstein S, Changeux JP (2003) An H-bond between two residues from different loops of the acetylcholine binding site contributes to the activation mechanism of nicotinic receptors. EMBO J 22:1990–2003
Paas Y, Gibor G, Grailhe R, Savatier-Duclert N, Dufresne V et al (2005) Pore conformations and gating mechanism of a Cys-loop receptor. Proc Natl Acad Sci USA 102:15877–15882
Cymes GD, Ni Y, Grosman C (2005) Probing ion-channel pores one proton at a time. Nature 438:975–980
Cymes GD, Grosman C (2008) Pore-opening mechanism of the nicotinic acetylcholine receptor evinced by proton transfer. Nat Struct Mol Biol 15:389–396
Beckstein O, Sansom MS (2006) A hydrophobic gate in an ion channel: the closed state of the nicotinic acetylcholine receptor. Phys Biol 3:147–159
Ivanov I, Cheng X, Sine SM, McCammon JA (2007) Barriers to ion translocation in cationic and anionic receptors from the Cys-loop family. J Am Chem Soc 129:8217–8224
White BH, Cohen JB (1992) Agonist-induced changes in the structure of the acetylcholine receptor M2 regions revealed by photoincorporation of an uncharged nicotinic noncompetitive antagonist. J Biol Chem 267:15770–15783
Plazas PV, De Rosa MJ, Gomez-Casati ME, Verbitsky M, Weisstaub N, Katz E, Bouzat C, Elgoyhen AB (2005) Key roles of hydrophobic rings of TM2 in gating of the alpha9alpha10 nicotinic cholinergic receptor. Br J Pharmacol 145:963–974
Corry B (2006) An energy-efficient gating mechanism in the acetylcholine receptor channel suggested by molecular and Brownian dynamics. Biophys J 90:799–810
Cheng X, Ivanov I, Wang H, Sine SM, McCammon JA (2007) Nanosecond-timescale conformational dynamics of the human alpha7 nicotinic acetylcholine receptor. Biophys J 93:2622–2634
Jha A, Purohit P, Auerbach A (2009) Energy and structure of the M2 helix in acetylcholine receptor-channel gating. Biophys J 96:4075–4084
Roth R, Gillespie D, Nonner W, Eisenberg RE (2008) Bubbles, gating, and anesthetics in ion channels. Biophys J 94:4282–4298
Bouzat C, Gumilar F, Spitzmaul G, Wang HL, Rayes D, Hansen S, Taylor P, Sine SM (2004) Coupling of agonist binding to channel gating in an ACh-binding protein linked to ion channel. Nature 430:896–900
Bartos M, Rayes D, Bouzat C (2006) Molecular determinants of pyrantel selectivity in nicotinic receptors. Mol Pharmacol 70:1307–1318
Elenes S, Ni Y, Cymes GD, Grosman C (2006) Desensitization contributes to the synaptic response of gain-of-function mutants of the muscle nicotinic receptor. J Gen Physiol 128:615–627
Magleby KL, Pallotta BS (1981) A study of desensitization of acetylcholinereceptors using nerve-released transmitter in the frog. J Physiol (Lond) 316:225–250
Giniatullin R, Nistri A, Yakel JL (2005) Desensitization of nicotinic ACh receptors: shaping cholinergic signaling. Trends Neurosci 28:371–378
Gumilar F, Arias HR, Spitzmaul G, Bouzat C (2003) Molecular mechanisms of inhibition of nicotinic acetylcholine receptors by tricyclic antidepressants. Neuropharmacology 45:964–976
Spitzmaul G, Gumilar F, Dilger JP, Bouzat C (2009) The local anaesthetics proadifen and adiphenine inhibit nicotinic receptors by different molecular mechanisms. Br J Pharmacol 157:804–817
Xiu X, Hanek AP, Wang J, Lester HA, Dougherty DA (2005) A unified view of the role of electrostatic interactions in modulating the gating of Cys loop receptors. J Biol Chem 280:41655–41666
Cederholm JM, Schofield PR, Lewis TM (2009) Gating mechanisms in Cys-loop receptors. Eur Biophys J (in press)
Crawford DK, Perkins DI, Trudell JR, Bertaccini EJ, Davies DL, Alkana RL (2008) Roles for loop 2 residues of alpha1 glycine receptors in agonist activation. J Biol Chem 283:27698–27706
Kash TL, Jenkins A, Kelley JC, Trudell JR, Harrison NL (2003) Coupling of agonist binding to channel gating in the GABAA receptor. Nature 421:272–475
Lee WY, Sine SM (2005) Principal pathway coupling agonist binding to channel gating in nicotinic receptors. Nature 438:243–247
Fu DX, Sine SM (1996) Asymmetric contribution of the conserved disulfide loop to subunit oligomerization and assembly of the nicotinic acetylcholine receptor. J Biol Chem 271:31479–31484
Green WN, Wanamaker CP (1997) The role of the cystine loop in acetylcholine receptor assembly. J Biol Chem 272:20945–20953
Shen XM, Ohno K, Tsujino A, Brengman JM, Gingold M, Sine SM, Engel AG (2003) Mutation causing severe myasthenia reveals functional asymmetry of AChR signature cystine loops in agonist binding and gating. J Clin Invest 111:497–505
Chakrapani S, Bailey TD, Auerbach A (2004) Gating dynamics of the acetylcholine receptor extracellular domain. J Gen Physiol 123:341–356
Grutter T, de Carvalho LP, Dufresne V, Taly A, Edelstein SJ, Changeux JP (2005) Molecular tuning of fast gating in pentameric ligand-gated ion channels. Proc Natl Acad Sci USA 102:18207–18212
Jha A, Cadugan DJ, Purohit P, Auerbach A (2007) Acetylcholine receptor gating at extracellular transmembrane domain interface: the cys-loop and M2–M3 linker. J Gen Physiol 130:547–558
Lee WY, Free CR, Sine SM (2008) Nicotinic receptor interloop proline anchors beta1-beta2 and Cys loops in coupling agonist binding to channel gating. J Gen Physiol 132:265–728
Galzi JL, Bertrand S, Corringer PJ, Changeux JP, Bertrand D (1996) Identification of calcium binding sites that regulate potentiation of a neuronal nicotinic acetylcholine receptor. EMBO J 15:5824–5832
Lyford LK, Sproul AD, Eddins D, McLaughlin JT, Rosenberg RL (2003) Agonist-induced conformational changes in the extracellular domain of alpha7 nicotinic acetylcholine receptors. Mol Pharmacol 64:650–658
Hibbs RE, Radic Z, Taylor P, Johnson DA (2006) Influence of agonists and antagonists on the segmental motion of residues near the agonist binding pocket of the acetylcholine-binding protein. J Biol Chem 281:39708–39718
Mercado J, Czajkowski C (2006) Charged residues in the alpha1 and beta2 pre-M1 regions involved in GABAA receptor activation. J Neurosci 26:2031–2040
Castaldo P, Stefanoni P, Miceli F, Coppola G, Del Giudice EM, Bellini G, Pascotto A, Trudell JR, Harrison NL, Annunziato L, Taglialatela M (2004) A novel hyperekplexia-causing mutation in the pre-transmembrane segment 1 of the human glycine receptor alpha1 subunit reduces membrane expression and impairs gating by agonists. J Biol Chem 279:25598–25604
Hu XQ, Zhang L, Stewart RR, Weight FF (2003) Arginine 222 in the pre-transmembrane domain 1 of 5-HT3A receptors links agonist binding to channel gating. J Biol Chem 278:46583–46589
Campos-Caro A, Sala S, Ballesta JJ, Vicente-Agulló F, Criado M, Sala F (1996) A single residue in the M2–M3 loop is a major determinant of coupling between binding and gating in neuronal nicotinic receptors. Proc Natl Acad Sci USA 93:6118–6123
Castillo M, Mulet J, Gutiérrez LM, Ortiz JA, Castelán F, Gerber S, Sala S, Sala F, Criado M (2006) Role of the RIC-3 protein in trafficking of serotonin and nicotinic acetylcholine receptors. J Mol Neurosci 30:153–156
Lummis SC, Beene DL, Lee LW, Lester HA, Broadhurst RW, Dougherty DA (2005) Cis–trans isomerization at a proline opens the pore of a neurotransmitter-gated ion channel. Nature 438:248–252
Kash TL, Kim T, Trudell JR, Harrison NL (2004) Evaluation of a proposed mechanism of ligand-gated ion channel activation in the GABAA and glycine receptors. Neurosci Lett 371:230–234
Lynch JW, Rajendra S, Pierce KD, Handford CA, Barry PH, Schofield PR (1997) Identification of intracellular and extracellular domains mediating signal transduction in the inhibitory glycine receptor chloride channel. EMBO J 16:110–120
Shiang R, Ryan SG, Zhu YZ, Fielder TJ, Allen RJ, Fryer A, Yamashita S, O'Connell P, Wasmuth JJ (1995) Mutational analysis of familial and sporadic hyperekplexia. Ann Neurol 38:85–91
Elmslie FV, Hutchings SM, Spencer V, Curtis A, Covanis T, Gardiner RM, Rees M (1996) Analysis of GLRA1 in hereditary and sporadic hyperekplexia: a novel mutation in a family cosegregating for hyperekplexia and spastic paraparesis. J Med Genet 33:435–436
Blanton MP, Cohen JB (1992) Mapping the lipid-exposed regions in the Torpedo californica nicotinic acetylcholine receptor. Biochemistry 31:3738–3750
Blanton MP, Cohen JB (1994) Identifying the lipid–protein interface of the Torpedo nicotinic acetylcholine receptor: secondary structure implications. Biochemistry 33:2859–2872
Bouzat C, Roccamo AM, Garbus I, Barrantes FJ (1998) Mutations at lipid-exposed residues of the acetylcholine receptor affect its gating kinetics. Mol Pharmacol 54:146–153
Bouzat C, Gumilar F, del Esandi MC, Sine SM (2002) Subunit-selective contribution to channel gating of the M4 domain of the nicotinic receptor. Biophys J 82:1920–1929
Mitra A, Bailey TD, Auerbach AL (2004) Structural dynamics of the M4 transmembrane segment during acetylcholine receptor gating. Structure 12:1909–1918
Reeves DC, Jansen M, Bali M, Lemster T, Akabas MH (2005) A role for the beta1–beta2 loop in the gating of 5-HT3 receptors. J Neurosci 25:9358–9366
Schreiber G, Fersht AR (1995) Energetics of protein–protein interactions: analysis of the barnase–barstar interface by single mutations and double mutant cycles. J Mol Biol 248:478–486
Wang J, Lester HA, Dougherty DA (2007) Establishing an ion pair interaction in the homomeric rho1 gamma-aminobutyric acid type A receptor that contributes to the gating pathway. J Biol Chem 282:26210–26216
Price KL, Millen KS, Lummis SC (2007) Transducing agonist binding to channel gating involves different interactions in 5-HT3 and GABAC receptors. J Biol Chem 282:25623–25630
Lee WY, Free CR, Sine SM (2009) Binding to gating transduction in nicotinic receptors: Cys-loop energetically couples to pre-M1 and M2–M3 regions. J Neurosci 29:3189–3199
Melis C, Bussi G, Lummis SC, Molteni C (2009) Trans–cis switching mechanisms in proline analogues and their relevance for the gating of the 5-HT(3) receptor. J Phys Chem B 113:12148–12153
Paulsen IM, Martin IL, Dunn SM (2009) Isomerization of the proline in the M2–M3 linker is not required for activation of the human 5-HT3A receptor. J Neurochem 110:870–878
Bafna PA, Purohit PG, Auerbach A (2008) Gating at the mouth of the acetylcholine receptor channel: energetic consequences of mutations in the alphaM2-cap. PLoS ONE 3:e2515
Zouridakis M, Zisimopoulou P, Poulas K, Tzartos SJ (2009) Recent advances in understanding the structure of nicotinic acetylcholine receptors. IUBMB Life 61:407–423
Nishizaki T (2003) N-Glycosylation sites on the nicotinic ACh receptor subunits regulate receptor channel desensitization and conductance. Brain Res Mol Brain Res 114:172–176
Acknowledgments
This work was supported by grants from CONICET, Universidad Nacional del Sur, Agencia Nacional de Promoción Científica y Tecnológica, and Fundación Florencio Fiorini to CB.
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Mariana Bartos and Jeremías Corradi contributed equally to this work.
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Bartos, M., Corradi, J. & Bouzat, C. Structural Basis of Activation of Cys-Loop Receptors: the Extracellular–Transmembrane Interface as a Coupling Region. Mol Neurobiol 40, 236–252 (2009). https://doi.org/10.1007/s12035-009-8084-x
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DOI: https://doi.org/10.1007/s12035-009-8084-x