STRUCTURE-FUNCTION OF THE CARDIAC SODIUM CHANNEL

心脏钠通道的结构与功能

• 批准号: 6651134
• 负责人: HARRY A FOZZARD
• 金额: $ 33.47万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-29 至 2005-05-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6651134
• 关键词: Xenopus oocyte; binding sites; cardiac myocytes; cardiotoxin; cell line; gene mutation; membrane permeability; mutant; protein isoforms; protein structure function; sodium channel

DESCRIPTION (the applicant's description verbatim): The long-term purpose of this project is to understand cardiac Na+ channel function at the molecular level, and to use the understanding to develop strategies for control of lethal arrhythmias. This project has three interdependent goals for the next five years: 1) resolving the molecular configuration of the Na+ channel permeation path/selectivity region, including the sites for local anesthetic drug binding, 2) examining the roles of charged vestibule residues in permeation and selectivity, and 3) determining the functional abnormalities resulting from naturally occurring channel mutants, especially alpha-subunit interactions. The Na+ channel is a major participant in most serious or lethal arrhythmias, and it is the target of some of our most powerful antiarrhythmic drugs. Considerable progress has been made in identifying the molecular structure of the outer vestibule (outer third of the permeation path) by effects of point mutations on permeation and selectivity and by determining the complimentary surface for binding of the pore-blocking toxins. Our unifying structural hypothesis is that the Na+ channel is related through evolution to the structurally determined KcsA bacterial channel, and that it spore motif of a helix teepee and a selectivity motif of helix-turn-strand is applicable to the Na+ channel. We propose to extend the complimentary interaction surface for outer vestibule toxins to identify the structure of the "turrets" in the outer path, perhaps also attempting to resolve the isoform selectivity of u-conotoxin in the process. These important carboxyls in the outer vestibule will be examined by mutation and pH titration for their contribution to dehydration of the permeating ions. The residues facing the inner pore will be identified by sequential mutation of the residues to cysteine, with access determined by methanesulfonate derivative interaction. Their roles in local anesthetic drug binding will be determined, in order to find all of the molecular parts of the drug binding site. State-dependent access of these residues will be examined to determine the changes in the site with channel gating. Each experimental step is developed based on the best molecular model we can develop, and in turn the model is improved as new experimental information is obtained in these experiments or published by others.

描述(申请人的逐字描述)：长期目的 本课题旨在从分子水平上了解心肌钠离子通道功能 水平，并利用这一理解来制定控制致命疾病的战略 心律不齐。该项目在接下来的五年中有三个相互依赖的目标 年：1)解决Na+通道渗透的分子构型 路径/选择性区域，包括局部麻醉剂药物结合部位， 2)检查带电前庭残留物在渗透和 选择性，以及3)确定由以下原因引起的功能异常 自然产生的通道突变，特别是阿尔法亚单位相互作用。这个 Na+通道是大多数严重或致命性心律失常的主要参与者， 它是我们一些最有效的抗心律失常药物的靶点。 在鉴定其分子结构方面已经取得了相当大的进展 外前庭(外三分之一的渗透路径)受穴位的影响 关于渗透性和选择性的突变以及通过确定补充性 用于结合堵塞毛孔的毒素的表面。我们统一的结构 假设钠离子通道在进化过程中与 结构上确定了KCSA细菌通道，它的孢子模体是一种 螺旋被盖和螺旋-转向链的选择性基序适用于 Na+通道。我们建议将互补交互曲面扩展为 外部前庭毒素识别外部“炮塔”的结构 PATH，也许也试图解决U-芋螺毒素的异构体选择性 在这个过程中。这些位于外前庭的重要羧基将是 通过突变和pH滴定检测它们对脱水率的贡献 渗透的离子。朝向内孔的残留物将通过以下方式识别 残基顺序突变为半胱氨酸，其访问权限由 甲烷磺酸盐衍生物相互作用。它们在局麻药中的作用 结合将被确定，以便找到所有分子部分 药物结合部位。国家对这些残留物的依赖访问将被审查为 确定使用通道门控的站点中的更改。每一个实验步骤 是基于我们可以开发的最好的分子模型开发的，反过来 随着新的实验信息的获得，模型得到了改进 实验或由他人发表。