Assembly limits the pharmacological complexity of ATP-sensitive potassium channels
Assembly limits the pharmacological complexity of ATP-sensitive potassium channels
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DOI：
10.1074/jbc.m112209200
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发表时间：
2002-04-19
影响因子：
4.8
通讯作者：
Tinker, A
中科院分区：
文献类型：
--
作者：
Giblin, JP;Cui, Y;Tinker, A
ATP敏感性钾通道（K（ATP）通道）由内向整流钾（+）通道（Kir6.1、Kir6.2）和磺酰脲受体（SUR 1、SUR 2A和SUR 2B）的八聚体复合物形成。在这项研究中，我们试图解决的问题，是否SUR异源多聚体可以使用生物化学和电生理方法相结合的形式。我们在HEK 293细胞中构建了共表达Kir6.2与SUR 1和SUR 2A的单克隆稳定细胞系。使用免疫共沉淀分析与SUR同种型特异性抗体的两个生化群体进行区分，一个含有SUR 1和其他SUR 2A。不可能检测到同时含有SUR 1和SUR 2A的免疫复合物。进行功能研究，并使用膜片钳研究全细胞膜电流。测定选择性抑制或激活SUR 1/Kir6.2和SUR 2A/Kir6.2的磺酰脲类和钾通道开放剂的浓度。在表达SUR 1/SUR 2A-Kir 6.2的细胞系中，我们无法证明具有独特药理学性质的通道群。因此，我们从这些研究中得出结论，含有SUR 1和SUR 2A的异源多聚体通道复合物没有形成，表明不同SUR亚型之间的不相容性。这种不相容性限制了可能在天然组织中观察到的K（ATP）通道的药理学复杂性。
ATP-sensitive potassium channels (K(ATP) channels) are formed from an octameric complex of an inwardly rectifying K(+) channel (Kir6.1, Kir6.2) and a sulfonylurea receptor (SUR1, SUR2A, and SUR2B). In this study we have attempted to address the question of whether SUR heteromultimers can form using a combination of biochemical and electrophysiological approaches. We have constructed monoclonal stable lines in HEK293 cells coexpressing Kir6.2 with SUR1 and SUR2A. Using coimmunoprecipitation analysis with SUR isotype-specific antibodies two biochemical populations are distinguished, one containing SUR1 and the other SUR2A. It is not possible to detect immune complexes containing both SUR1 and SUR2A. Functional studies were undertaken and whole cell membrane currents were studied using the patch clamp. Concentrations of sulfonylureas and potassium channel openers were determined that selectively inhibited or activated SUR1/Kir6.2 and SUR2A/Kir6.2. In the cell line expressing SUR1/SUR2A-Kir6.2 we were unable to demonstrate a population of channels with unique pharmacological properties. Thus we conclude from these studies that heteromultimeric channel complexes containing both SUR1 and SUR2A are not formed, suggesting an incompatibility between different SUR subtypes. This incompatibility limits the pharmacological complexity of K(ATP) channels that may be observed in native tissues.