Single-Channel Properties of Recombinant Acid-Sensitive Ion Channels Formed by the Subunits Asic2 and Asic3 from Dorsal Root Ganglion Neurons Expressed in Xenopus Oocytes

Single-Channel Properties of Recombinant Acid-Sensitive Ion Channels Formed by the Subunits Asic2 and Asic3 from Dorsal Root Ganglion Neurons Expressed in Xenopus Oocytes

The acid-sensitive ion channels known as ASIC are gated by external protons. A set of these channels is expressed in dorsal root ganglion neurons where they may participate in the transduction of mechanical and nociceptive stimuli. Here, we have examined the single-channel properties of channels for...

Full description

Bibliographic Details
Main Authors: Zhang, Ping, Canessa, Cecilia M.
Format: Online
Language:English
Published: The Rockefeller University Press 2001
Online Access:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2232399/
id pubmed-2232399
recordtype oai_dc
spelling pubmed-22323992008-04-21 Single-Channel Properties of Recombinant Acid-Sensitive Ion Channels Formed by the Subunits Asic2 and Asic3 from Dorsal Root Ganglion Neurons Expressed in Xenopus Oocytes Zhang, Ping Canessa, Cecilia M. Original Article The acid-sensitive ion channels known as ASIC are gated by external protons. A set of these channels is expressed in dorsal root ganglion neurons where they may participate in the transduction of mechanical and nociceptive stimuli. Here, we have examined the single-channel properties of channels formed by the subunits ASIC2 and ASIC3 expressed in Xenopus oocytes using outside-out patches. The mean single-channel current-voltage relationship is linear with a slope conductance of 18 pS between −80 and −40 mV in 150 mM Na+ outside and 150 mM K+ inside the patch pipet. The selectivity for monovalent cations has the sequence Na+ > Li+ > K+. Divalent cations such as Ca2+ do not permeate, but instead block the channel when applied to the extracellular side. External protons increase the probability of channels being open to a maximum of 0.8 with an EC50 of 16 ± 4 μM and a Hill coefficient of 2.7 ± 0.3, whereas the mean single-channel current amplitude is independent of external pH. Analysis of the kinetics of single channels indicates the presence of at least four modes of activity (Mod1 to Mod4) in addition to an inactivated state. Three of the modes exhibit distinct kinetics, and can be unambiguously identified on the basis of open probability (PoMod1 = 0.5 ± 0.05; PoMod2 > 0.9 ± 0.05; PoMod3 < 0.1). Mode 4, which has a Po in the range of 0.5–0.8, may constitute a distinct mode or alternatively, it represents transitions between the other three modes of activity. Increasing [H+]o increases the frequency of entering the modes with high Po (modes 1, 2, and 4) and the time the channel spends in the modes with high activity. The Rockefeller University Press 2001-06-01 /pmc/articles/PMC2232399/ /pubmed/11382806 Text en © 2001 The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
repository_type Open Access Journal
institution_category Foreign Institution
institution US National Center for Biotechnology Information
building NCBI PubMed
collection Online Access
language English
format Online
author Zhang, Ping
Canessa, Cecilia M.
spellingShingle Zhang, Ping
Canessa, Cecilia M.
Single-Channel Properties of Recombinant Acid-Sensitive Ion Channels Formed by the Subunits Asic2 and Asic3 from Dorsal Root Ganglion Neurons Expressed in Xenopus Oocytes
author_facet Zhang, Ping
Canessa, Cecilia M.
author_sort Zhang, Ping
title Single-Channel Properties of Recombinant Acid-Sensitive Ion Channels Formed by the Subunits Asic2 and Asic3 from Dorsal Root Ganglion Neurons Expressed in Xenopus Oocytes
title_short Single-Channel Properties of Recombinant Acid-Sensitive Ion Channels Formed by the Subunits Asic2 and Asic3 from Dorsal Root Ganglion Neurons Expressed in Xenopus Oocytes
title_full Single-Channel Properties of Recombinant Acid-Sensitive Ion Channels Formed by the Subunits Asic2 and Asic3 from Dorsal Root Ganglion Neurons Expressed in Xenopus Oocytes
title_fullStr Single-Channel Properties of Recombinant Acid-Sensitive Ion Channels Formed by the Subunits Asic2 and Asic3 from Dorsal Root Ganglion Neurons Expressed in Xenopus Oocytes
title_full_unstemmed Single-Channel Properties of Recombinant Acid-Sensitive Ion Channels Formed by the Subunits Asic2 and Asic3 from Dorsal Root Ganglion Neurons Expressed in Xenopus Oocytes
title_sort single-channel properties of recombinant acid-sensitive ion channels formed by the subunits asic2 and asic3 from dorsal root ganglion neurons expressed in xenopus oocytes
description The acid-sensitive ion channels known as ASIC are gated by external protons. A set of these channels is expressed in dorsal root ganglion neurons where they may participate in the transduction of mechanical and nociceptive stimuli. Here, we have examined the single-channel properties of channels formed by the subunits ASIC2 and ASIC3 expressed in Xenopus oocytes using outside-out patches. The mean single-channel current-voltage relationship is linear with a slope conductance of 18 pS between −80 and −40 mV in 150 mM Na+ outside and 150 mM K+ inside the patch pipet. The selectivity for monovalent cations has the sequence Na+ > Li+ > K+. Divalent cations such as Ca2+ do not permeate, but instead block the channel when applied to the extracellular side. External protons increase the probability of channels being open to a maximum of 0.8 with an EC50 of 16 ± 4 μM and a Hill coefficient of 2.7 ± 0.3, whereas the mean single-channel current amplitude is independent of external pH. Analysis of the kinetics of single channels indicates the presence of at least four modes of activity (Mod1 to Mod4) in addition to an inactivated state. Three of the modes exhibit distinct kinetics, and can be unambiguously identified on the basis of open probability (PoMod1 = 0.5 ± 0.05; PoMod2 > 0.9 ± 0.05; PoMod3 < 0.1). Mode 4, which has a Po in the range of 0.5–0.8, may constitute a distinct mode or alternatively, it represents transitions between the other three modes of activity. Increasing [H+]o increases the frequency of entering the modes with high Po (modes 1, 2, and 4) and the time the channel spends in the modes with high activity.
publisher The Rockefeller University Press
publishDate 2001
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2232399/
_version_ 1611438212478140416

Similar Items