SLOW INACTIVATION OF SODIUM CHANNELS

本研究的长期目标是分析结构-功能 钠离子通道的关系，并将这些与疾病的相关性 兴奋性本提案的具体实验目的是 在缓慢失活期间产生通道构象的物理模型， 并包括：1）测试的假设，即（a）S4 4跨膜 段在缓慢期间处于其去极化有利位置 失活，（B）通过静电产生缓慢失活 两个或多个S4跨膜带电荷残基之间的相互作用 节段;（2）测试假设（a）缓慢失活是有限的 通过III-IV细胞内连接体和 S4跨膜，（B）将结构域III-IV胞内接头分段 在缓慢失活期间处于结合位置;（3）测试 假设与慢波相关的特定通道相互作用 失活可以从骨骼肌/心肌通道定位 嵌合体实现这些目标所采用的方法包括 结合分子生物学操纵钠通道 钠离子结构和电生理学（膜片钳）评估 通道功能这一建议的健康相关性是，钠 通道形成神经，肌肉， 和分泌细胞，缓慢失活是一个关键的决定因素， 可用于打开的通道的数量，因此， 兴奋性钠通道对细胞兴奋性的影响 突变导致多种疾病状态，包括非营养不良性 肌强直心律失常和癫痫兴奋性差异 钠离子通道亚型之间的相互作用也可能形成放电模式的基础 和突触后整合在中枢神经系统，证明，或 怀疑，是许多这些差异的基础，在细胞 兴奋性然而，缓慢失活的结构基础， 以及它与其他钠通道特性的相互作用， 未知钠离子通道慢流时构象的物理模型 这一提议将产生消极影响， 关于缓慢失活的结构基质的信息。这 信息是开发治疗方法至关重要的第一步 以及对钠的基本认识 通道功能

The long-term goal of this research are to analyze structure-function relationships in the sodium channel, and to correlate these to diseases of excitability. The specific experimental aims of this proposal are to produce physical models of channel conformation during slow inactivation, and include: 1) testing the hypothesis that (a) the S4 4 membrane-spanning segments are in their depolarized-favored position during slow inactivation, (b) that slow inactivation is produced by electrostatic interactions between charged residues in two or more S4 membrane-spanning segments; (2) testing the hypothesis that (a) slow inactivation is limited by electrostatic interactions between the III-IV intracellular linker and S4 membrane-spanning, (b) segments the domain III-IV intracellular linker is in the bound position during slow inactivation; (3) testing the hypothesis that specific channel interactions associated with slow inactivation can be localized from skeletal muscle/cardiac muscle channel chimeras. The methodology that will be used to achieve these aims includes a combination of molecular biological manipulation of sodium channel structure and electrophysiological (patch clamp) assessment of sodium channel function. The health-relatedness of this proposal is that sodium channels form the primary basis for action potentials in nerves, muscles, and secretory cells, and that slow inactivation is a critical determinant of the number of channels available for opening and, therefore, cell excitability. Modification of cell excitability due to sodium channel mutations leads to a variety of disease states including non-dystrophic myotonia, cardiac arrhythmia, and epilepsy. Differences in excitability amongst sodium channel subtypes may also form the basis of firing patterns and post-synaptic integration in the central nervous system, proven, or suspected, to be the basis of many of these differences in cell excitability. However, the structural underpinnings of slow inactivation, and its interactions with other sodium channel properties, as yet remain unknown. The physical models of sodium channel conformation during slow inactivation that this proposal will produce contribute crucial information regarding the structural substrates of slow inactivation. This information is a critically-necessary first step to developing treatments for diseases of excitability and to a basic understanding of sodium channel function.