Rectification & Block of Ion Channel Currents

描述(申请人提供)：内向整流钾(KIR)通道调节许多组织中的兴奋性，一些疾病是由KIR通道基因突变引起的。在之前的获奖期间，我们证明了可溶细胞质因子在强大的内向整流器中引起内在整流，确认这些因素是多胺，并证实它们起到了阻断通道渗透途径的‘长孔堵塞’的作用。最近两种不同K通道孔结构的结晶揭示了K通道的渗透和门控机制。然而，整顿和关闭KIR渠道的结构细节仍不清楚。初步数据引导我们对多胺的分子细节-KIR通道中整流的诱导和配体门控机制的具体假设。这些假说将在三个实验目标上得到严格的检验，利用生化和生物物理技术的组合，以及分子建模来获得以前无法获得的对内向整流和门控机制的洞察。这项工作将为通过调节KIR通道活性来开发合理的治疗心律失常、癫痫和其他细胞兴奋性障碍的方法提供信息。

DESCRIPTION (provided by applicant): Inward rectifying K (Kir) channels regulate excitability in many tissues, and several diseases result from mutations of Kir channel genes. During previous award periods we demonstrated that soluble cytoplasmic factors cause intrinsic rectification in strong inward rectifiers, identified these factors as polyamines, and confirmed that they act as 'long-pore plugs' to block the channel permeation pathway. Recent crystallization of two different K channel pore structures has illuminated mechanisms of permeation and gating in K channels. However, the structural details of rectification and of gating in Kir channels remain unclear. Preliminary data lead us to specific hypotheses regarding the molecular details of polyamine-induction of rectification and of ligand-gating mechanisms in Kir channels. These hypotheses will be critically examined in three experimental Aims, utilizing a combination of biochemical and biophysical techniques, together with molecular modeling to gain previously unobtainable insight to the mechanisms of inward rectification and gating. The work will provide information that will form the background to the development of rational therapies for cardiac arrhythmias, epilepsy and other disorders of cell excitability through modulation of Kir channel activity.