Mg2+ binding to open and closed states can activate BK channels provided that the voltage sensors are elevated.

Tunghai University Institutional Repository > 理學院 > 生命科學系所 > 期刊論文 > Item 310901/28954

請使用永久網址來引用或連結此文件: http://140.128.103.80:8080/handle/310901/28954

題名:	Mg2+ binding to open and closed states can activate BK channels provided that the voltage sensors are elevated.
作者:	陳仁祥 Chen, Ren-Shiang Geng, Yanyan Karl, L.Magleby
貢獻者:	Department of Physiology and Biophysics, University of Miami Miller School of Medicine
關鍵詞:	BK channel Mg2+ Ca2+
日期:	2011-12
上傳時間:	2016-11-24T01:07:19Z (UTC)
出版者:	US:The Rockefeller University Press
摘要:	BK channels are activated by intracellular Ca2+ and Mg2+ as well as by depolarization. Such activation is possible because each of the four subunits has two high-affinity Ca2+ sites, one low-affinity Mg2+ site, and a voltage sensor. This study further investigates the mechanism of Mg2+ activation by using single-channel recording to determine separately the action of Mg2+ on the open and closed states of the channel. To limit Mg2+ action to the Mg2+ sites, the two high-affinity Ca2+ sites are disabled by mutation. When the voltage is stepped from negative holding potentials to +100 mV, we find that 10 mM Mg2+ decreases the mean closed latency to the first channel opening 2.1-fold, decreases the mean closed interval duration 8.7-fold, increases mean burst duration 10.1-fold, increases the number of openings per burst 4.4-fold, and increases mean open interval duration 2.3-fold. Hence, Mg2+ can bind to closed BK channels, increasing their opening rates, and to open BK channels, decreasing their closing rates. To explore the relationship between Mg2+ action and voltage sensor activation, we record single-channel activity in macropatches containing hundreds of channels. Open probability (Po) is dramatically increased by 10 mM Mg2+ when voltage sensors are activated with either depolarization or the mutation R210C. The increased Po arises from large decreases in mean closed interval durations and moderate increases in mean open interval durations. In contrast, 10 mM Mg2+ has no detectable effects on Po or interval durations when voltage sensors are deactivated with very negative potentials or the mutation R167E. These observations are consistent with a model in which Mg2+ can bind to and alter the gating of both closed and open states to increase Po, provided that one or more voltage sensors are activated.
關聯:	Journal of General Physiology, 138(6), 593-607
顯示於類別:	[生命科學系所] 期刊論文

文件中的檔案:

檔案	描述	大小	格式	瀏覽次數
index.html		0Kb	HTML	243	檢視/開啟

檢視Licence

在THUIR中所有的資料項目都受到原著作權保護.

資料載入中.....