Multiple Ca(2+)-binding sites in the extracellular domain of the Ca(2+)-sensing receptor corresponding to cooperative Ca(2+) response.
Multiple Ca(2+)-binding sites in the extracellular domain of the Ca(2+)-sensing receptor corresponding to cooperative Ca(2+) response.
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DOI：
10.1021/bi8014604
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发表时间：
2009-01-20
期刊：
影响因子：
2.9
通讯作者：
Yang, Jenny J.
中科院分区：
文献类型：
--
作者：
Huang, Yun;Zhou, Yubin;Castiblanco, Adriana;Yang, Wei;Brown, Edward M.;Yang, Jenny J.
细胞外 Ca2+ 浓度 ([Ca2+]o) 的微小变化会通过激活 Ca2+ 传感受体 (CaSR) 将细胞信号反应整合到多个细胞和组织网络中并发挥功能。主要通过 Ca2+ 与二聚体 CaSR 的大胞外结构域 (ECD) 结合，细胞内 Ca2+ 反应与 2 至 4 的表观 Hill 系数高度配合。我们之前报道过，通过将 CaSR 衍生的 Ca2+ 结合肽移植到不结合 Ca2+ 的支架蛋白 CD2 上，鉴定了两个连续的假定 Ca2+ 结合位点。在本文中，我们预测 ECD 中存在更多潜在的非连续 Ca2+ 结合位点。我们将完整的 CaSR 分解为三个球状子域，每个子域包含 2 到 3 个预测的 Ca2+ 结合位点。这种方法使我们能够进一步了解多种金属离子与源自 CaSR ECD 内的延伸多肽结合的机制，预计这将更接近地模拟天然 CaSR ECD 的结构。 Tb3+-发光能量转移、ANS 荧光和 NMR 研究表明这些子域中存在双相金属结合成分和 Ca2+ 依赖性构象变化。去除位点 1 和位点 3 中预测的 Ca2+ 结合配体分别废除了第一个结合步骤和第二个结合步骤。对这些子结构域的研究表明，存在多个金属结合位点和金属诱导的构象变化，这些变化可能是通过在开放非活性形式和封闭活性形式之间转变来打开/关闭 CaSR 的原因。
A small change in the extracellular Ca2+ concentration ([Ca2+]o) integrates cell signaling responses in multiple cellular and tissue networks and functions via activation of Ca2+-sensing receptors (CaSR). Mainly through binding of Ca2+ to the large extracellular domain (ECD) of the dimeric CaSR, intracellular Ca2+ responses are highly cooperative with an apparent Hill coefficient ranging from 2 to 4. We have previously reported the identification of two continuous putative Ca2+-binding sites by grafting CaSR-derived, Ca2+-binding peptides to a scaffold protein, CD2, that does not bind Ca2+. In this paper, we predict more potential non-continuous Ca2+-binding sites in the ECD. We dissect the intact CaSR into three globular subdomains, each of which contains 2 to 3 predicted Ca2+-binding sites. This approach enables us to further understand the mechanisms underlying the binding of multiple metal ions to extended polypeptides derived from within the ECD of the CaSR, which would be anticipated to more closely mimic the structure of the native CaSR ECD. Tb3+-luminescence energy transfer, ANS fluorescence, and NMR studies show biphasic metal-binding components and Ca2+-dependent conformational changes in these subdomains. Removing the predicted Ca2+-binding ligands in site 1 and site 3 abolishes the first binding step and second binding step, respectively. Studies on these subdomains suggest the existence of multiple metal-binding sites and metal-induced conformational changes that might be responsible for switching on/off the CaSR by transition between its open inactive form and closed active form.
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影响因子：
14.9
作者：
Kopp, J;Schwede, T
通讯作者：
Schwede, T
影响因子：
4.8
作者：
Mun, HC;Franks, AH;Conigrave, AD
通讯作者：
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影响因子：
4
作者：
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通讯作者：
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影响因子：
5.6
作者：
BABU, YS;BUGG, CE;COOK, WJ
通讯作者：
COOK, WJ
DOI：
10.1152/ajprenal.2000.279.6.f1083
发表时间：
2000-12-01
影响因子：
4.2
作者：
Handlogten, ME;Shiraishi, N;Miller, RT
通讯作者：
Miller, RT