Key roles of hydrophobic rings of TM2 in gating of the α9α10 nicotinic cholinergic receptor
We have performed a systematic mutagenesis of three hydrophobic rings (17′, 13′ and 9′) within transmembrane region (TM) 2 of the α9α10 nicotinic cholinergic receptor (nAChR) to a hydrophilic (threonine) residue and compared the properties of mutant receptors reconstituted in Xenopus laevis oocytes....
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2005
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00071188_v145_n7_p963_Plazas http://hdl.handle.net/20.500.12110/paper_00071188_v145_n7_p963_Plazas |
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paper:paper_00071188_v145_n7_p963_Plazas2023-06-08T14:31:37Z Key roles of hydrophobic rings of TM2 in gating of the α9α10 nicotinic cholinergic receptor Plazas, Paola Viviana Gómez Casati, María Eugenia Verbitsky, Miguel Weisstaub, Noelia V. Katz, Eleonora Acetylcholine Channel gating Cys-loop receptors Ionotropic receptors Nicotinic receptors nicotinic receptor partial agonist tropisetron animal cell article channel gating controlled study electric organ extracellular calcium hydrophilicity hydrophobicity ion transport membrane potential nonhuman phenotype priority journal ring opening Xenopus laevis Acetylcholine Allosteric Regulation Amino Acid Sequence Animals Calcium Cholinergic Agents Dose-Response Relationship, Drug Ion Channel Gating Membrane Potentials Molecular Sequence Data Mutagenesis, Site-Directed Oocytes Patch-Clamp Techniques Phenotype Protein Subunits Receptors, Nicotinic Recombinant Proteins Sequence Alignment Transfection Xenopus laevis We have performed a systematic mutagenesis of three hydrophobic rings (17′, 13′ and 9′) within transmembrane region (TM) 2 of the α9α10 nicotinic cholinergic receptor (nAChR) to a hydrophilic (threonine) residue and compared the properties of mutant receptors reconstituted in Xenopus laevis oocytes. Phenotypic changes in α9α10 mutant receptors were evidenced by a decrease in the desensitization rate, an increase in both the EC 50 for ACh as well as the efficacy of partial agonists and the reduction of the allosteric modulation by extracellular Ca 2+. Mutated receptors exhibited spontaneous openings and, at the single-channel level, an increased apparent mean open time with no major changes in channel conductance, thus suggesting an increase in gating of the channel as the underlying mechanism. Overall, the degrees of the phenotypes of mutant receptors were more overt in the case of the centrally located V13′T mutant. Based on the atomic model of the pore of the electric organ of the Torpedo ray, we can propose that the interactions of side chains at positions 13′ and 9′ are key ones in creating an energetic barrier to ion permeation. In spite of the fact that the roles of the TM2 residues are mostly conserved in the distant α9α10 member of the nAChR family, their mechanistic contributions to channel gating show significant differences when compared to other nAChRs. These differences might be originated from slight differential intramolecular rearrangements during gating for the different receptors and might lead each nAChR to be in tune with their physiological roles. © 2005 Nature Publishing Group All rights reserved. Fil:Plazas, P.V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Gomez-Casati, M.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Verbitsky, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Weisstaub, N. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Katz, E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2005 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00071188_v145_n7_p963_Plazas http://hdl.handle.net/20.500.12110/paper_00071188_v145_n7_p963_Plazas |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Acetylcholine Channel gating Cys-loop receptors Ionotropic receptors Nicotinic receptors nicotinic receptor partial agonist tropisetron animal cell article channel gating controlled study electric organ extracellular calcium hydrophilicity hydrophobicity ion transport membrane potential nonhuman phenotype priority journal ring opening Xenopus laevis Acetylcholine Allosteric Regulation Amino Acid Sequence Animals Calcium Cholinergic Agents Dose-Response Relationship, Drug Ion Channel Gating Membrane Potentials Molecular Sequence Data Mutagenesis, Site-Directed Oocytes Patch-Clamp Techniques Phenotype Protein Subunits Receptors, Nicotinic Recombinant Proteins Sequence Alignment Transfection Xenopus laevis |
| spellingShingle |
Acetylcholine Channel gating Cys-loop receptors Ionotropic receptors Nicotinic receptors nicotinic receptor partial agonist tropisetron animal cell article channel gating controlled study electric organ extracellular calcium hydrophilicity hydrophobicity ion transport membrane potential nonhuman phenotype priority journal ring opening Xenopus laevis Acetylcholine Allosteric Regulation Amino Acid Sequence Animals Calcium Cholinergic Agents Dose-Response Relationship, Drug Ion Channel Gating Membrane Potentials Molecular Sequence Data Mutagenesis, Site-Directed Oocytes Patch-Clamp Techniques Phenotype Protein Subunits Receptors, Nicotinic Recombinant Proteins Sequence Alignment Transfection Xenopus laevis Plazas, Paola Viviana Gómez Casati, María Eugenia Verbitsky, Miguel Weisstaub, Noelia V. Katz, Eleonora Key roles of hydrophobic rings of TM2 in gating of the α9α10 nicotinic cholinergic receptor |
| topic_facet |
Acetylcholine Channel gating Cys-loop receptors Ionotropic receptors Nicotinic receptors nicotinic receptor partial agonist tropisetron animal cell article channel gating controlled study electric organ extracellular calcium hydrophilicity hydrophobicity ion transport membrane potential nonhuman phenotype priority journal ring opening Xenopus laevis Acetylcholine Allosteric Regulation Amino Acid Sequence Animals Calcium Cholinergic Agents Dose-Response Relationship, Drug Ion Channel Gating Membrane Potentials Molecular Sequence Data Mutagenesis, Site-Directed Oocytes Patch-Clamp Techniques Phenotype Protein Subunits Receptors, Nicotinic Recombinant Proteins Sequence Alignment Transfection Xenopus laevis |
| description |
We have performed a systematic mutagenesis of three hydrophobic rings (17′, 13′ and 9′) within transmembrane region (TM) 2 of the α9α10 nicotinic cholinergic receptor (nAChR) to a hydrophilic (threonine) residue and compared the properties of mutant receptors reconstituted in Xenopus laevis oocytes. Phenotypic changes in α9α10 mutant receptors were evidenced by a decrease in the desensitization rate, an increase in both the EC 50 for ACh as well as the efficacy of partial agonists and the reduction of the allosteric modulation by extracellular Ca 2+. Mutated receptors exhibited spontaneous openings and, at the single-channel level, an increased apparent mean open time with no major changes in channel conductance, thus suggesting an increase in gating of the channel as the underlying mechanism. Overall, the degrees of the phenotypes of mutant receptors were more overt in the case of the centrally located V13′T mutant. Based on the atomic model of the pore of the electric organ of the Torpedo ray, we can propose that the interactions of side chains at positions 13′ and 9′ are key ones in creating an energetic barrier to ion permeation. In spite of the fact that the roles of the TM2 residues are mostly conserved in the distant α9α10 member of the nAChR family, their mechanistic contributions to channel gating show significant differences when compared to other nAChRs. These differences might be originated from slight differential intramolecular rearrangements during gating for the different receptors and might lead each nAChR to be in tune with their physiological roles. © 2005 Nature Publishing Group All rights reserved. |
| author |
Plazas, Paola Viviana Gómez Casati, María Eugenia Verbitsky, Miguel Weisstaub, Noelia V. Katz, Eleonora |
| author_facet |
Plazas, Paola Viviana Gómez Casati, María Eugenia Verbitsky, Miguel Weisstaub, Noelia V. Katz, Eleonora |
| author_sort |
Plazas, Paola Viviana |
| title |
Key roles of hydrophobic rings of TM2 in gating of the α9α10 nicotinic cholinergic receptor |
| title_short |
Key roles of hydrophobic rings of TM2 in gating of the α9α10 nicotinic cholinergic receptor |
| title_full |
Key roles of hydrophobic rings of TM2 in gating of the α9α10 nicotinic cholinergic receptor |
| title_fullStr |
Key roles of hydrophobic rings of TM2 in gating of the α9α10 nicotinic cholinergic receptor |
| title_full_unstemmed |
Key roles of hydrophobic rings of TM2 in gating of the α9α10 nicotinic cholinergic receptor |
| title_sort |
key roles of hydrophobic rings of tm2 in gating of the α9α10 nicotinic cholinergic receptor |
| publishDate |
2005 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00071188_v145_n7_p963_Plazas http://hdl.handle.net/20.500.12110/paper_00071188_v145_n7_p963_Plazas |
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| _version_ |
1768543114250682368 |