2-aminoethoxydiphenyl borate alters selectivity of Orai3 channels by increasing their pore size
2-aminoethoxydiphenyl borate alters selectivity of Orai3 channels by increasing their pore size
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DOI：
10.1074/jbc.m803101200
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发表时间：
2008-07-18
影响因子：
4.8
通讯作者：
Romanin, Christoph
中科院分区：
文献类型：
--
作者：
Schindl, Rainer;Bergsmann, Judith;Romanin, Christoph
内质网中的 Stim1 和质膜中的三个 Orai（也称为 CRACM）通道是天然 Ca2+ 释放激活的 Ca2+ 通道的主要组成部分。这些通道的药理学特征是它们对 2-氨基乙氧基二苯基硼酸盐 (2-APB) 的独特敏感性。在这里，我们报告Orai3电流可以被75μM 2-APB独立于Stim1强烈刺激，而相似浓度的2-APB抑制存储操作的Orai1电流。 2-APB 不仅促进通过 Orai3 通道的电流，而且还显着改变 Orai3 通道的离子选择性。这允许单价阳离子向内和向外方向渗透，这与存储操作的 Orai3 电流的高 Ca2+ 选择性形成鲜明对比。 Orai3-R66W 突变体与严重联合免疫缺陷突变体 Orai1-R91W 库操作激活缺乏相似性，也被发现对 2-APB 刺激具有抵抗力。 2-APB 选择性的变化与 Orai3 最小孔径从约 3.8 A 增加到超过 5.34 A 相关。与 2-APB 与 Orai3 孔的潜在相互作用一致，在测试的三个孔突变体中，Orai3 E165Q 突变体的渗透特性与 2-APB 刺激的 Orai3 的渗透特性特别相似，并且还表现出对 2-APB 的响应降低。总的来说，2-APB 对 Orai3 电流的刺激伴随着渗透途径的改变，这代表了通过化合物调节离子通道选择性的独特机制。
Stim1 in the endoplasmic reticulum and the three Orai (also termed CRACM) channels in the plasma-membrane are main components of native Ca2+ release-activated Ca2+ channels. A pharmacological hallmark of these channels is their distinct sensitivity to 2-aminoethoxydiphenyl borate (2-APB). Here we report that Orai3 currents can be robustly stimulated by 75 mu M 2-APB independent of Stim1, whereas 2-APB at similar concentrations inhibited store-operated Orai1 currents. 2-APB did not only promote currents through Orai3 channels but also dramatically altered ion selectivity of Orai3 channels. This allowed for permeation of monovalent cations both in the inward as well as outward direction, which is in sharp contrast to the high Ca2+ selectivity of store-operated Orai3 currents. An Orai3-R66W mutant, which lacked in analogy to the severe combined immune deficiency mutant Orai1-R91W store-operated activation, was also found to be resistant to 2-APB stimulation. The change in selectivity by 2-APB was associated with an increase in Orai3 minimum pore size from about 3.8 A to more than 5.34 A. In line with a potential interaction of 2-APB with the Orai3 pore, among three pore mutants tested, the Orai3 E165Q mutant particularly resembled in its permeation properties those of 2-APB stimulated Orai3 and additionally exhibited a reduced response to 2-APB. In aggregate, stimulation of Orai3 currents by 2-APB occurred along with an alteration of the permeation pathway that represents a unique mechanism for regulating ion channel selectivity by chemical compounds.