MOLECULAR PHARMACOLOGY OF VOLTAGE SENSITIVE NA CHANNELS

描述：调节选择性渗透性的电压敏感通道 TO-Na+(NAV通道)是膜蛋白家族的成员，该家族 为神经、肌肉电兴奋提供生理基础 还有心。NAV通道的医学意义在于 它们是几类药物和神经毒素的靶标，例如 局麻药、抗心律失常药、河豚毒素和麻黄毒素。从基因上讲 有缺陷的NAV通道也是各种人类肌肉和 心脏疾病，如高血钾性周期性麻痹、副肌张力、 先天遗传和长QT综合征。对导航航道的研究已经有了相当大的进展 加深我们对通道蛋白是如何受电压和 它们如何调节Call膜的离子通透性。从长远来看 本项目的目标是阐明离子渗透的分子基础。 以及毒素和药物与NAV通道的相互作用。近年来， 在理解NAV通道如何发挥作用方面取得了重大进展 区分Na+、K+和Ca2+。一个被称为‘DEKA’的结构主题 由同源结构域I-IV上的四个残基组成的‘基因座’已被 被发现在这一过程中起着关键作用。这样做的具体目的是 1.分析DEKA基因座在离子交换中的作用 辨别和选择性渗透性。2.定义静电 外前庭带电残留物对离子的贡献 无机阳离子的选择性、电导性和外部封闭。3. 研究DEKA基因与有机和无机的相互作用 从内侧阻挡NAV通道的阳离子。要实现这些目标 大鼠骨骼肌异构体的AIMS、天然和突变NAV通道将 在培养的哺乳动物细胞系中表达。宏观和 单通道电流将采用全电池、贴片和平面记录 双层记录技术。相对渗透率和封闭性 各种阳离子的相互作用将被系统地分析为特定的 DEKA基因和外前庭的突变。这些生物物理 研究将使我们能够推断关键残基的功能贡献 它们决定了NAV通道的离子选择性和单位电导 毛孔。

DESCRIPTION: Voltage-sensitive channels that mediate selective permeability to Na+ (NaV channels) are members of a family of membrane proteins that provide the physiological basis for electrical excitation in nerve, muscle and heart. The medical significance of NaV channels lies in the fact that they are the target of several classes of drugs and neurotoxins such as local anesthetics, antiarrhythmics, tetrodotoxin and saxitoxin. Genetically defective NaV channels are also responsible for various human muscle and heart disorders such as hyperkalemic periodic paralysis, paramyotonia, congenita, and long QT syndrome. Research on NaV channels has considerably advance our understanding of how channel proteins are gated by voltage and how they regulate the ionic permeability of call membranes. The long term goal of this project is to elucidate the molecular basis of ion permeation and the interaction of toxins and drugs with NaV channels. In recent years, there have been major advances in understanding how NaV channels discriminate among Na+, K+, and Ca2+. A structural motif termed the 'DEKA locus' that is composed of four residues in homologous domains I-IV has been found to play a critical role in this process. The specific aims of this project are to: 1. Analyze the function of the DEKA locus in ion discrimination and selective permeability. 2. Define the electrostatic contribution of charged residues in the outer vestibule to ionic selectivity, conductance, and external block by inorganic cations. 3. Investigate the interaction of the DEKA locus with organic and inorganic cations that block NaV channels from the internal side. To achieve these aims, native and mutant NaV channels of the rat skeletal muscle isoform will be expressed in a cultured mammalian cell line. Macroscopic and single-channel currents will be recorded by whole-cell, patch, and planar bilayer recording techniques. The relative permeability and blocking interactions of various cations will be systematically analyzed for specific mutations of the DEKA locus and the outer vestibule. These biophysical studies will allow us deduce the functional contribution of key residues that determine ionic selectivity and unitary conductance of the NaV channel pore.