N-terminal transmembrane domain of SUR1 controls gating of Kir6.2 by modulating channel sensitivity to PIP2.
N-terminal transmembrane domain of SUR1 controls gating of Kir6.2 by modulating channel sensitivity to PIP2.
复制标题
DOI：
10.1085/jgp.201010557
复制
发表时间：
2011-03
期刊：
影响因子：
--
通讯作者：
Shyng SL
中科院分区：
文献类型：
--
作者：
Pratt EB;Tewson P;Bruederle CE;Skach WR;Shyng SL
胰腺ATP敏感性钾通道的功能完整性依赖于成孔钾通道亚基Kir6.2和调节亚基磺酰脲受体1（SUR 1）之间的相互作用。以前的研究表明，N-末端跨膜结构域的SUR 1（TMD 0）与Kir6.2相互作用，并足以赋予高的内在开放概率（Po）和爆发模式的活动中观察到的全长KATP通道。然而，TMD 0-Kir6.2相互作用的性质，门控调制的基础是没有很好地理解。使用两个先前描述的致病突变TMD 0（R74 W和E128 K），我们进行了氨基酸取代，以研究这些残基在KATP通道功能的全长SUR 1以及TMD 0的背景下的结构作用。我们的研究结果表明，尽管全长SUR 1中的R74 W和E128 K都降低了表面通道的表达，并降低了通道对ATP抑制的敏感性，但它们通过不同的机制到达那里。R74的突变一致地降低了TMD 0蛋白水平，表明R74对于TMD 0的稳定性是必需的。相反，E128突变保留了TMD 0蛋白水平，但减少了TMD 0和Kir6.2形成的mini-KATP通道中TMD 0和Kir6.2之间的功能偶联。重要的是，E128 K全长通道尽管具有大大降低的Po，但对磷脂酰肌醇4，5-二磷酸（PIP 2）刺激几乎没有反应。这让人想起在不存在SUR 1的情况下Kir6.2通道的行为，并表明TMD 0通过调节Kir6.2与PIP 2的相互作用来控制Kir6.2门控。进一步支持这一观点，全长通道中的E128 W突变导致通道失活，其被外源性PIP 2阻止或逆转。这些结果确定了TMD 0中的一个关键决定因素，其通过控制通道对PIP 2的敏感性来控制Kir6.2门控。此外，他们发现了一种新的KATP通道失活机制，涉及SUR 1和Kir6.2之间的异常功能偶联。
Functional integrity of pancreatic adenosine triphosphate (ATP)-sensitive potassium (KATP) channels depends on the interactions between the pore-forming potassium channel subunit Kir6.2 and the regulatory subunit sulfonylurea receptor 1 (SUR1). Previous studies have shown that the N-terminal transmembrane domain of SUR1 (TMD0) interacts with Kir6.2 and is sufficient to confer high intrinsic open probability (Po) and bursting patterns of activity observed in full-length KATP channels. However, the nature of TMD0–Kir6.2 interactions that underlie gating modulation is not well understood. Using two previously described disease-causing mutations in TMD0 (R74W and E128K), we performed amino acid substitutions to study the structural roles of these residues in KATP channel function in the context of full-length SUR1 as well as TMD0. Our results revealed that although R74W and E128K in full-length SUR1 both decrease surface channel expression and reduce channel sensitivity to ATP inhibition, they arrive there via distinct mechanisms. Mutation of R74 uniformly reduced TMD0 protein levels, suggesting that R74 is necessary for stability of TMD0. In contrast, E128 mutations retained TMD0 protein levels but reduced functional coupling between TMD0 and Kir6.2 in mini-KATP channels formed by TMD0 and Kir6.2. Importantly, E128K full-length channels, despite having a greatly reduced Po, exhibit little response to phosphatidylinositol 4,5-bisphosphate (PIP2) stimulation. This is reminiscent of Kir6.2 channel behavior in the absence of SUR1 and suggests that TMD0 controls Kir6.2 gating by modulating Kir6.2 interactions with PIP2. Further supporting this notion, the E128W mutation in full-length channels resulted in channel inactivation that was prevented or reversed by exogenous PIP2. These results identify a critical determinant in TMD0 that controls Kir6.2 gating by controlling channel sensitivity to PIP2. Moreover, they uncover a novel mechanism of KATP channel inactivation involving aberrant functional coupling between SUR1 and Kir6.2.
登录
查看更多内容
DOI：
10.1085/jgp.200308878
发表时间：
2003-11
期刊：
The Journal of general physiology
影响因子：
--
作者：
Enkvetchakul D;Nichols CG
通讯作者：
Nichols CG
影响因子：
3.4
作者：
Enkvetchakul, D;Loussouarn, G;Nichols, CG
通讯作者：
Nichols, CG
影响因子：
56.9
作者：
Baukrowitz, T;Schulte, U;Fakler, B
通讯作者：
Fakler, B
影响因子：
4.8
作者：
Du, XO;Zhang, HL;Logothetis, DE
通讯作者：
Logothetis, DE
DOI：
10.1073/pnas.051499698
发表时间：
2001-02-27
影响因子：
11.1
作者：
Cartier, EA;Conti, LR;Shyng, SL
通讯作者：
Shyng, SL