Analysis of minK & MiRP Regulation of Cardiac K Channels

描述（由申请人提供）：人们越来越认识到离子通道辅助蛋白在调节心律中的重要性。MinK和相关的MiRPs是由KCNE基因家族编码的K+通道调节剂。它们可以与两个长QT相关的延迟整流器（HERG和KvLQT 1）、起搏通道（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综合征和单核苷酸多态性的联系所强调，这可能使患者对药物诱导的心律失常敏感。KCNEs各自编码具有单个跨膜片段的小的整合膜蛋白，这表明它们以同源方式与K+通道相互作用。然而，它们的序列同源性相当不同，只有分散的保守区域。突变已经向我们展示了KCNE 1和2中几个重要的功能位点。关于结构-功能关系、化学计量和体内特定蛋白质-蛋白质相互作用仍存在争议。通过研究KCNE-通道相互作用的确切机制，可以加深对LQTS、药物性心律失常和获得性心律失常的理解。为此，我们建议： 1)确定KvLQT 1和HERG的特定区域，这些区域在物理和功能上与minK和/或MiRPs相互作用。 2)确定minK/MiRP与HERG或KvLQTI之间的伴侣相对偏好。 3)在生化和电生理研究中使用表位标记的KCNEs和嵌合体确定通道复合物的化学计量。 4)分析minK/MiRPs与HERG和KvLQT 1的共表达模式及其在心肌细胞中的关联。

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.