Mapping the BKCa channel's "Ca2+ bowl": side-chains essential for Ca2+ sensing.
Mapping the BKCa channel's "Ca2+ bowl": side-chains essential for Ca2+ sensing.
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DOI：
10.1085/jgp.200409052
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发表时间：
2004-05
期刊：
影响因子：
--
通讯作者：
Cox DH
中科院分区：
文献类型：
--
作者：
Bao L;Kaldany C;Holmstrand EC;Cox DH
关于Ca~(2+)是否与BKCa通道的胞内区或整膜区结合，以及降低通道对Ca~(2+)敏感性的突变是否在Ca~(2+)配位点起作用，都存在争议。细胞内域中与钙离子感应有关的一个区域是“钙碗”。该区域包含许多酸性残基，而大的钙-碗突变通过一种似乎是高亲和力的钙结合部位消除了对钙的感知。在这里，通过定点突变，我们已经定位了钙碗中对钙离子感知最重要的残基。我们发现酸性残基D898和D900是必不可少的，我们发现它们对于钙离子与包含BKCa通道细胞内结构域一部分的融合蛋白的结合也是必不可少的。因此，我们的许多数据支持这样的结论，即Ca~(2+)与BKCa通道的胞内结构域结合，它们定义了Ca~(2+)碗的基本钙敏感基序。然而，总体而言，我们发现破坏钙感知的突变和破坏钙结合的突变之间的关系并不像我们预期的那么强，这一结果增加了这样一种可能性，即当用凝胶覆盖法检查时，钙碗可能处于非本机构象。
There is controversy over whether Ca2+ binds to the BKCa channel's intracellular domain or its integral-membrane domain and over whether or not mutations that reduce the channel's Ca2+ sensitivity act at the point of Ca2+ coordination. One region in the intracellular domain that has been implicated in Ca2+ sensing is the “Ca2+ bowl”. This region contains many acidic residues, and large Ca2+-bowl mutations eliminate Ca2+ sensing through what appears to be one type of high-affinity Ca2+-binding site. Here, through site-directed mutagenesis we have mapped the residues in the Ca2+ bowl that are most important for Ca2+ sensing. We find acidic residues, D898 and D900, to be essential, and we find them essential as well for Ca2+ binding to a fusion protein that contains a portion of the BKCa channel's intracellular domain. Thus, much of our data supports the conclusion that Ca2+ binds to the BKCa channel's intracellular domain, and they define the Ca2+ bowl's essential Ca2+-sensing motif. Overall, however, we have found that the relationship between mutations that disrupt Ca2+ sensing and those that disrupt Ca2+ binding is not as strong as we had expected, a result that raises the possibility that, when examined by gel-overlay, the Ca2+ bowl may be in a nonnative conformation.
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影响因子：
3.8
作者：
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通讯作者：
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影响因子：
2.9
作者：
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影响因子：
2.7
作者：
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通讯作者：
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影响因子：
16.2
作者：
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通讯作者：
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DOI：
10.1085/jgp.116.3.411
发表时间：
2000-09
期刊：
The Journal of general physiology
影响因子：
--
作者：
Cox DH;Aldrich RW
通讯作者：
Aldrich RW