Measurements of the BKCa channel's high-affinity Ca2+ binding constants: effects of membrane voltage.
Measurements of the BKCa channel's high-affinity Ca2+ binding constants: effects of membrane voltage.
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DOI：
10.1085/jgp.200810094
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发表时间：
2008-11
影响因子：
3.8
通讯作者：
Cox, Daniel H.
中科院分区：
文献类型：
--
作者：
Sweet, Tara-Beth;Cox, Daniel H.
已经确定的是，大电导Ca 2+激活的K+通道包含两种类型的高亲和力Ca 2+结合位点，称为Ca 2+碗和RCK 1位点。这些网站的亲和力，以及它们如何随着频道的开放而变化，仍然是一个有争议的话题。以前的估计，这些亲和力依赖于拟合一系列的电导-电压关系，确定了一系列的Ca 2+浓度与模型的通道门控，包括电压传感和Ca 2+结合。这种方法要求选择某种电压感测模型，并且电压感测模型的选择的差异可能是已经产生的不同估计的基础。在这里，为了更好地确定这些亲和力，我们测量了野生型mSlo通道（减去其低亲和力Ca 2+结合位点）和通过突变禁用一个或另一个Ca 2+结合位点的通道在恒定电压下的通道活性的Ca 2+剂量响应曲线。为了准确地确定这些剂量-反应曲线，我们使用了一系列22个Ca 2+浓度，我们使用了单一的电流记录，再加上通道表达水平的变化，以测量超过五个数量级的开放概率。我们的研究结果表明，在-80 mV时，Ca 2+碗对Ca 2+的亲和力高于通道的开放和闭合构象中的RCK 1位点，并且Ca 2+与RCK 1位点的结合是电压依赖性的，而在Ca 2+碗中则不是。
It has been established that the large conductance Ca2+-activated K+ channel contains two types of high-affinity Ca2+ binding sites, termed the Ca2+ bowl and the RCK1 site. The affinities of these sites, and how they change as the channel opens, is still a subject of some debate. Previous estimates of these affinities have relied on fitting a series of conductance–voltage relations determined over a series of Ca2+ concentrations with models of channel gating that include both voltage sensing and Ca2+ binding. This approach requires that some model of voltage sensing be chosen, and differences in the choice of voltage-sensing model may underlie the different estimates that have been produced. Here, to better determine these affinities we have measured Ca2+ dose–response curves of channel activity at constant voltage for the wild-type mSlo channel (minus its low-affinity Ca2+ binding site) and for channels that have had one or the other Ca2+ binding site disabled via mutation. To accurately determine these dose–response curves we have used a series of 22 Ca2+ concentrations, and we have used unitary current recordings, coupled with changes in channel expression level, to measure open probability over five orders of magnitude. Our results indicate that at −80 mV the Ca2+ bowl has higher affinity for Ca2+ than does the RCK1 site in both the opened and closed conformations of the channel, and that the binding of Ca2+ to the RCK1 site is voltage dependent, whereas at the Ca2+ bowl it is not.
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DOI：
10.1085/jgp.109.5.647
发表时间：
1997-05
期刊：
The Journal of general physiology
影响因子：
--
作者：
Cui J;Cox DH;Aldrich RW
通讯作者：
Aldrich RW
MG2+增强了BK通道中的电压传感器/门耦合。
影响因子：
3.8
作者：
Horrigan, Frank T.;Ma, Zhongming
通讯作者：
Ma, Zhongming
影响因子：
3.4
作者：
Kim, Hyun-Ju;Lim, Hyun-Ho;Park, Chul-Seung
通讯作者：
Park, Chul-Seung
影响因子：
5.3
作者：
Hu, H;Shao, LR;Storm, JF
通讯作者：
Storm, JF
影响因子：
16.2
作者：
Jiang, YX;Pico, A;MacKinnon, R
通讯作者：
MacKinnon, R