Activation and inhibition of TMEM16A calcium-activated chloride channels.
Calcium-activated chloride channels (CaCC) encoded by family members of transmembrane proteins of unknown function 16 (TMEM16) have recently been intensely studied for functional properties as well as their physiological roles as chloride channels in various tissues. One technical hurdle in studying...
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Public Library of Science (PLoS)
2014-01-01
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| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC3906059?pdf=render |
| _version_ | 1828865949761011712 |
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| author | Yu-Li Ni Ai-Seon Kuan Tsung-Yu Chen |
| author_facet | Yu-Li Ni Ai-Seon Kuan Tsung-Yu Chen |
| author_sort | Yu-Li Ni |
| collection | DOAJ |
| description | Calcium-activated chloride channels (CaCC) encoded by family members of transmembrane proteins of unknown function 16 (TMEM16) have recently been intensely studied for functional properties as well as their physiological roles as chloride channels in various tissues. One technical hurdle in studying these channels is the well-known channel rundown that frequently impairs the precision of electrophysiological measurements for the channels. Using experimental protocols that employ fast-solution exchange, we circumvented the problem of channel rundown by normalizing the Ca(2+)-induced current to the maximally-activated current obtained within a time period in which the channel rundown was negligible. We characterized the activation of the TMEM16A-encoded CaCC (also called ANO1) by Ca(2+), Sr(2+), and Ba(2+), and discovered that Mg(2+) competes with Ca(2+) in binding to the divalent-cation binding site without activating the channel. We also studied the permeability of the ANO1 pore for various anions and found that the anion occupancy in the pore-as revealed by the permeability ratios of these anions-appeared to be inversely correlated with the apparent affinity of the ANO1 inhibition by niflumic acid (NFA). On the other hand, the NFA inhibition was neither affected by the degree of the channel activation nor influenced by the types of divalent cations used for the channel activation. These results suggest that the NFA inhibition of ANO1 is likely mediated by altering the pore function but not through changing the channel gating. Our study provides a precise characterization of ANO1 and documents factors that can affect divalent cation activation and NFA inhibition of ANO1. |
| first_indexed | 2024-12-13T04:40:06Z |
| format | Article |
| id | doaj.art-c9fa1eb23e9e4f61afb213db52cbc9ac |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-13T04:40:06Z |
| publishDate | 2014-01-01 |
| publisher | Public Library of Science (PLoS) |
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| series | PLoS ONE |
| spelling | doaj.art-c9fa1eb23e9e4f61afb213db52cbc9ac2022-12-21T23:59:21ZengPublic Library of Science (PLoS)PLoS ONE1932-62032014-01-0191e8673410.1371/journal.pone.0086734Activation and inhibition of TMEM16A calcium-activated chloride channels.Yu-Li NiAi-Seon KuanTsung-Yu ChenCalcium-activated chloride channels (CaCC) encoded by family members of transmembrane proteins of unknown function 16 (TMEM16) have recently been intensely studied for functional properties as well as their physiological roles as chloride channels in various tissues. One technical hurdle in studying these channels is the well-known channel rundown that frequently impairs the precision of electrophysiological measurements for the channels. Using experimental protocols that employ fast-solution exchange, we circumvented the problem of channel rundown by normalizing the Ca(2+)-induced current to the maximally-activated current obtained within a time period in which the channel rundown was negligible. We characterized the activation of the TMEM16A-encoded CaCC (also called ANO1) by Ca(2+), Sr(2+), and Ba(2+), and discovered that Mg(2+) competes with Ca(2+) in binding to the divalent-cation binding site without activating the channel. We also studied the permeability of the ANO1 pore for various anions and found that the anion occupancy in the pore-as revealed by the permeability ratios of these anions-appeared to be inversely correlated with the apparent affinity of the ANO1 inhibition by niflumic acid (NFA). On the other hand, the NFA inhibition was neither affected by the degree of the channel activation nor influenced by the types of divalent cations used for the channel activation. These results suggest that the NFA inhibition of ANO1 is likely mediated by altering the pore function but not through changing the channel gating. Our study provides a precise characterization of ANO1 and documents factors that can affect divalent cation activation and NFA inhibition of ANO1.http://europepmc.org/articles/PMC3906059?pdf=render |
| spellingShingle | Yu-Li Ni Ai-Seon Kuan Tsung-Yu Chen Activation and inhibition of TMEM16A calcium-activated chloride channels. PLoS ONE |
| title | Activation and inhibition of TMEM16A calcium-activated chloride channels. |
| title_full | Activation and inhibition of TMEM16A calcium-activated chloride channels. |
| title_fullStr | Activation and inhibition of TMEM16A calcium-activated chloride channels. |
| title_full_unstemmed | Activation and inhibition of TMEM16A calcium-activated chloride channels. |
| title_short | Activation and inhibition of TMEM16A calcium-activated chloride channels. |
| title_sort | activation and inhibition of tmem16a calcium activated chloride channels |
| url | http://europepmc.org/articles/PMC3906059?pdf=render |
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