Analysis of minK & MiRP Regulation of Cardiac K Channels

描述(申请人提供)：人们越来越意识到离子通道辅助蛋白在调节心律中的重要性。Mink及其相关的MIRP是由KCNE家族基因编码的K+通道调节器。它们可以与两个长QT相关延迟整流(HERG和KvLQT1)、起搏器通道(HCN)和各种电压门控K+通道相互作用。它们的重要性被与遗传性长QT综合征和可能使患者对药物引起的心律失常敏感的单核苷酸多态联系起来。每个KCNE编码具有一个跨膜片段的小的完整膜蛋白，这表明它们与K+通道以同源方式相互作用。然而，它们的序列同源性相当不同，只有零星的保守区。突变向我们展示了KCNE1&2功能所需的几个重要位点。关于结构-功能关系、化学计量学和体内特定的蛋白质-蛋白质相互作用仍然存在争议。通过研究KCNE-通道相互作用的精确机制，可能会对LQTS、药物诱发和获得性心律失常有更深入的了解。为此，我们建议： 1)确定KvLQT1和HERG与水貂和/或MIRP在物理和功能上相互作用的特定区域。 2)确定水貂/MIRP与HERG或KvLQTI在伙伴中的相对偏好。 3)在生化和电生理研究中使用表位标记的KCNE和嵌合体测定通道复合体的化学计量学。 4)分析Mink/MiRPs与HERG和KvLQT1在心肌细胞中的共表达模式及其相互关系。

DESCRIPTION (provided by applicant): There is increasing awareness of the importance of ion channel accessory proteins in regulating heart rhythm. MinK and the related MiRPs are K+ channel regulators encoded by the KCNE family of genes. They can interact with the two Long QT-associated delayed rectifiers (HERG and KvLQT1 ), pacemaker channels (HCNs) and a variety of voltage gated K+ channels. Their importance is underscored by linkage to hereditary Long QT syndrome and single nucleotide polymorphisms that may sensitize patients to drug-induced arrhythmias. KCNEs each encode small integral membrane proteins with a single transmembrane segment suggesting that they interact with K+ channels in homologous fashion. Their sequence homology however, is fairly divergent with only scattered areas of conservation. Mutations have shown us several of the important sites in KCNE1 & 2 required for function. Controversy remains regarding structure-function relations, stoichiometry and specific protein-protein interactions in vivo. By studying the precise mechanisms of KCNE-channel interaction, a deeper understanding of LQTS, drug-induced and acquired arrhythmias may be gained. To this end we propose to: 1) Determine the specific regions of KvLQT1 and HERG that physically and functionally interact with minK and/or MiRPs. 2) Determine the relative preferences in partners between minK/MiRPs and HERG or KvLQTI. 3) Determine channel complex stoichiometry using epitope-tagged KCNEs and chimeras in biochemical and electrophysiological studies. 4) Analyze the co-expression pattern of minK/MiRPs against that of HERG and KvLQT1 and their association in cardiac myocytes.