ION CHANNELS IN THE NERVOUS SYSTEM

电压门控钠通道（NAChs）对于神经系统中的电信号和传导至关重要。啮齿类动物中至少有10个NaCh基因，每个基因在人类中都有一个已知的直系同源物。每个NaCh亚型的具体作用是未知的。一种假设是亚型是差异分布和调制的。该建议的重点是脑NaCh亚型的调制和定位的分子基础。目的1的目标是鉴定与脑NaChs的胞质结构域（特别是Nav1.6）结合的蛋白质，并且负责（a）通道功能的调节和（B）靶向不同的亚细胞位点。两种互补的方法被用来发现和分离与氯化钠相关的蛋白质：（1）酵母双杂交测定法和（2）蛋白质纯化/质谱法。目的二是研究酵母双杂交技术分离的钙调素与氯化钠的相互作用。这种相互作用与脑氯化钠将其特征在于生化和电生理。目的3利用成像技术研究脑钠通道的亚细胞分布（特别是，Nav 1.6）及其结合蛋白。在表征这种分布后，将研究NaChs或目标I中确定的结合蛋白中突变的影响。这项研究具有基础科学和临床相关性。离子通道存在于与其他膜、细胞外和细胞内蛋白质的复合物中。为了理解这些通道的行为，重要的是要知道哪些蛋白质存在于这些复合物中，以及这些蛋白质如何与通道相互作用。肌肉中的NaChs突变导致骨骼肌的某些疾病和心肌中的长QT综合征。预计脑钠通道和与NaChs结合的蛋白质的突变将导致人类中枢神经系统疾病，拟议的研究将有助于我们对这些疾病的理解。

Voltage-gated sodium channels (NAChs) are vital for electrical signaling and conduction in the nervous system. There are at least ten NaCh genes in rodents, and each gene has a known ortholog in humans. The specific roles of each NaCh subtype are unknown. One hypothesis is that subtypes are differentially distributed and modulated. This proposal is focused upon the molecular basis for modulation and localization of brain NaCh subtypes. The goal of Aim 1 is to identify proteins that bind to the cytoplasmic domains of brain NaChs (esp. Nav1.6) and are responsible for (a) modulation of channel fiinction and (b) targeting to different subcellular sites. Two complementary methods are being used to find and isolate proteins associated with NaChs: (1) the yeast two-hybrid assay and (2) protein purification/mass spectrometry. Aim 2 is focused upon the interactions of NaChs with calmodulin, which was isolated with the yeast two-hybrid assay. This interaction with brain NaChs will be characterized biochemically and electrophysiologically. Aim 3 utilizes imaging techniques to study the subcellular distribution of brain sodium channels (esp., Nav 1.6) and their binding proteins. After characterizing this distribution, the effects of mutations in NaChs or in the binding proteins identified in Aim I will be studied. This research has both basic science and clinical relevance. Ion channels exist in complexes with other membrane, extracellular, and intracellular proteins. To understand the behavior of these channels, it is important to know which proteins are present in these complexes and hew the proteins interact with the channel. Mutations in muscle NaChs are responsible for some disorders of skeletal muscle and for long QT syndrome in cardiac muscle. It is expected that mutations in brain sodium channels and in the proteins that bind to NaChs will produce CNS disorders in humans, and the proposed studies will contribute to our understanding of these disorders.