SLOW INACTIVATION OF SODIUM CHANNELS

这项研究的长期目标是分析结构-功能 钠通道中的相互关系，并将这些关系与 兴奋性。这项提议的具体实验目的是 在缓慢失活期间产生通道构象的物理模型， 并包括：1)检验假设：(A)S4-4跨膜 在慢速期间，数据段处于其去极化的有利位置 失活，(B)缓慢失活是由静电引起的 两个或多个S4跨膜中带电残基之间的相互作用 分段；(2)检验以下假设：(A)缓慢失活是有限的 通过III-IV细胞内连接子和 S4跨膜，(B)分段结构域III-IV细胞内连接物 在缓慢停用期间处于绑定位置；(3)测试 假设特定的通道相互作用与慢速有关 失活可定位于骨骼肌/心肌通道 嵌合体。将用于实现这些目标的方法包括 钠离子通道的分子生物学操作组合 钠的结构和电生理(膜片钳)评价 通道功能。这项建议与健康相关的是钠 通道构成了神经、肌肉、 和分泌细胞，而缓慢的失活是一个关键的决定因素 可供打开的通道数量，因此，小区 兴奋性。钠通道对细胞兴奋性的影响 突变会导致多种疾病状态，包括非营养不良 肌强直、心律失常和癫痫。兴奋性的差异 其中钠通道亚型也可能构成放电模式的基础 以及中枢神经系统中的突触后整合，或 怀疑是许多细胞差异的基础 兴奋性。然而，缓慢失活的结构性基础， 以及它与其他钠通道特性的相互作用 未知。慢速时钠离子通道构象的物理模型 这项提案将产生的失活对 关于缓慢失活的结构底物的信息。这 信息是开发治疗方法至关重要的第一步 对兴奋性疾病和钠有一个基本的了解 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.