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Rapid resensitization of ASIC2a is conferred by three amino acid residues in the N terminus

Title
Rapid resensitization of ASIC2a is conferred by three amino acid residues in the N terminus
Authors
Lee, Jae SeungKweon, Hae JinLee, HyosangSuh, Byung-Chang
DGIST Authors
Lee, HyosangSuh, Byung-Chang
Issue Date
2019-07
Citation
Journal of General Physiology, 151(7), 944-953
Type
Article
Article Type
Article
Keywords
SENSING ION CHANNELSDESENSITIZATIONSELECTIVITYACTIVATIONCONTRIBUTETARGETSSITESH+
ISSN
0022-1295
Abstract
Acid-sensing ion channels (ASICs), sensory molecules that continuously monitor the concentration of extracellular protons and initiate diverse intracellular responses through an influx of cations, are assembled from six subtypes that can differentially combine to form various trimeric channel complexes and elicit unique electrophysiological responses. For instance, homomeric ASIC1a channels have been shown to exhibit prolonged desensitization, and acid-evoked currents become smaller when the channels are repeatedly activated by extracellular protons, whereas homomeric or heteromeric ASIC2a channels continue to respond to repetitive acidic stimuli without exhibiting such desensitization. Although previous studies have provided evidence that both the desensitization of ASIC1a and rapid resensitization of ASIC2a commonly require domains that include the N terminus and the first transmembrane region of these channels, the biophysical basis of channel gating at the amino acid level has not been clearly determined. Here, we confirm that domain-swapping mutations replacing the N terminus of ASIC2a with that of ASIC2b result in de novo prolonged desensitization in homomeric channels following activation by extracellular protons. Such desensitization of chimeric ASIC2a mutants is due neither to internalization nor to degradation of the channel proteins. We use site-directed mutagenesis to narrow down the relevant portion of the N terminus of ASIC2a, identifying three amino acid residues within the N terminus (T25, T39, and I40) whose mutation is sufficient to phenocopy the desensitization exhibited by the chimeric mutants. A similar desensitization is observed in heteromeric ASICs containing the mutant subunit. These results suggest that T25, T39, and I40 of ASIC2a are key residues determining the rapid resensitization of homomeric and heteromeric ASIC2a channels upon proton activation. © 2019 Lee et al.
URI
http://hdl.handle.net/20.500.11750/10385
DOI
10.1085/jgp.201812224
Publisher
Rockefeller University Press
Related Researcher
  • Author Suh, Byung-Chang Laboratory of Brain Signal and Synapse Research
  • Research Interests Molecular mechanisms of epilepsy and sensory pain transmission; Signaling mechanism of ion channel regulation and membrane excitability; 분자전기생리; 간질 및 통증의 분자적 기전 연구
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Collection:
Department of Brain and Cognitive SciencesLaboratory of Affective Neuroscience1. Journal Articles
Department of Brain and Cognitive SciencesLaboratory of Brain Signal and Synapse Research1. Journal Articles


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