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Snake neurotoxin α-bungarotoxin is an antagonist at native GABA(A) receptors
The snake neurotoxin α-bungarotoxin (α-Bgtx) is a competitive antagonist at nicotinic acetylcholine receptors (nAChRs) and is widely used to study their function and cell-surface expression. Increasingly, α-Bgtx is also used as an imaging tool for fluorophore-labelling studies, and given the structu...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Pergamon Press
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4398322/ https://www.ncbi.nlm.nih.gov/pubmed/25634239 http://dx.doi.org/10.1016/j.neuropharm.2015.01.001 |
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author | Hannan, Saad Mortensen, Martin Smart, Trevor G. |
author_facet | Hannan, Saad Mortensen, Martin Smart, Trevor G. |
author_sort | Hannan, Saad |
collection | PubMed |
description | The snake neurotoxin α-bungarotoxin (α-Bgtx) is a competitive antagonist at nicotinic acetylcholine receptors (nAChRs) and is widely used to study their function and cell-surface expression. Increasingly, α-Bgtx is also used as an imaging tool for fluorophore-labelling studies, and given the structural conservation within the pentameric ligand-gated ion channel family, we assessed whether α-Bgtx could bind to recombinant and native γ-aminobutyric type-A receptors (GABA(A)Rs). Applying fluorophore-linked α-Bgtx to recombinant αxβ1/2γ2 GABA(A)Rs expressed in HEK-293 cells enabled clear cell-surface labelling of α2β1/2γ2 contrasting with the weaker staining of α1/4β1/2γ2, and no labelling for α3/5/6β1/2γ2. The labelling of α2β2γ2 was abolished by bicuculline, a competitive antagonist at GABA(A)Rs, and by d-tubocurarine (d-Tc), which acts in a similar manner at nAChRs and GABA(A)Rs. Labelling by α-Bgtx was also reduced by GABA, suggesting that the GABA binding site at the receptor β–α subunit interface forms part of the α-Bgtx binding site. Using whole-cell recording, high concentrations of α-Bgtx (20 μM) inhibited GABA-activated currents at all αxβ2γ2 receptors examined, but at lower concentrations (5 μM), α-Bgtx was selective for α2β2γ2. Using α-Bgtx, at low concentrations, permitted the selective inhibition of α2 subunit-containing GABA(A)Rs in hippocampal dentate gyrus granule cells, reducing synaptic current amplitudes without affecting the GABA-mediated tonic current. In conclusion, α-Bgtx can act as an inhibitor at recombinant and native GABA(A)Rs and may be used as a selective tool to inhibit phasic but not tonic currents in the hippocampus. |
format | Online Article Text |
id | pubmed-4398322 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | Pergamon Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-43983222015-06-01 Snake neurotoxin α-bungarotoxin is an antagonist at native GABA(A) receptors Hannan, Saad Mortensen, Martin Smart, Trevor G. Neuropharmacology Article The snake neurotoxin α-bungarotoxin (α-Bgtx) is a competitive antagonist at nicotinic acetylcholine receptors (nAChRs) and is widely used to study their function and cell-surface expression. Increasingly, α-Bgtx is also used as an imaging tool for fluorophore-labelling studies, and given the structural conservation within the pentameric ligand-gated ion channel family, we assessed whether α-Bgtx could bind to recombinant and native γ-aminobutyric type-A receptors (GABA(A)Rs). Applying fluorophore-linked α-Bgtx to recombinant αxβ1/2γ2 GABA(A)Rs expressed in HEK-293 cells enabled clear cell-surface labelling of α2β1/2γ2 contrasting with the weaker staining of α1/4β1/2γ2, and no labelling for α3/5/6β1/2γ2. The labelling of α2β2γ2 was abolished by bicuculline, a competitive antagonist at GABA(A)Rs, and by d-tubocurarine (d-Tc), which acts in a similar manner at nAChRs and GABA(A)Rs. Labelling by α-Bgtx was also reduced by GABA, suggesting that the GABA binding site at the receptor β–α subunit interface forms part of the α-Bgtx binding site. Using whole-cell recording, high concentrations of α-Bgtx (20 μM) inhibited GABA-activated currents at all αxβ2γ2 receptors examined, but at lower concentrations (5 μM), α-Bgtx was selective for α2β2γ2. Using α-Bgtx, at low concentrations, permitted the selective inhibition of α2 subunit-containing GABA(A)Rs in hippocampal dentate gyrus granule cells, reducing synaptic current amplitudes without affecting the GABA-mediated tonic current. In conclusion, α-Bgtx can act as an inhibitor at recombinant and native GABA(A)Rs and may be used as a selective tool to inhibit phasic but not tonic currents in the hippocampus. Pergamon Press 2015-06 /pmc/articles/PMC4398322/ /pubmed/25634239 http://dx.doi.org/10.1016/j.neuropharm.2015.01.001 Text en © 2015 The Authors http://creativecommons.org/licenses/by/4.0/ This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Hannan, Saad Mortensen, Martin Smart, Trevor G. Snake neurotoxin α-bungarotoxin is an antagonist at native GABA(A) receptors |
title | Snake neurotoxin α-bungarotoxin is an antagonist at native GABA(A) receptors |
title_full | Snake neurotoxin α-bungarotoxin is an antagonist at native GABA(A) receptors |
title_fullStr | Snake neurotoxin α-bungarotoxin is an antagonist at native GABA(A) receptors |
title_full_unstemmed | Snake neurotoxin α-bungarotoxin is an antagonist at native GABA(A) receptors |
title_short | Snake neurotoxin α-bungarotoxin is an antagonist at native GABA(A) receptors |
title_sort | snake neurotoxin α-bungarotoxin is an antagonist at native gaba(a) receptors |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4398322/ https://www.ncbi.nlm.nih.gov/pubmed/25634239 http://dx.doi.org/10.1016/j.neuropharm.2015.01.001 |
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