MOLECULAR BASIS OF POTASSIUM CHANNEL ACTIVATION

钾通道激活的分子基础

• 批准号: 2190030
• 负责人: TOSHINORI HOSHI
• 金额: $ 18.85万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-08-01 至 1999-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2190030
• 关键词: Xenopus; Xenopus oocyte; adenosine triphosphate; chemical binding; chemical kinetics; chimeric proteins; divalent cations; gene mutation; mathematical model; membrane potentials; model design /development; molecular site; potassium channel; protein isoforms; protein structure function; site directed mutagenesis; voltage /patch clamp; voltage gated channel

Potassium channels are universally found in biological systems and play major roles in the cellular signal transduction process. The generally decrease the membrane excitability by clamping the membrane voltage near the potassium equilibrium voltage. Functional properties of the potassium channels can ultimately influence how the organism responds to its environment. Several different potassium channels have been characterized. Inward-rectifier potassium channels open in response to hyperpolarization and they are involved in maintaining normal resting potential. By influencing the resting potential, these inward-rectifier channels regulate the cellular excitability. Fore example, in heart muscle, the inward-rectifier channels greatly influence the rhythmicity, effectiveness of various antiarrhythmic agents, and the action potential conduction. The proposed research focuses on the cloned inward-rectifier potassium channel (KAT1) expressed in a heterologous expression system. The goal of the research is to understand how this channel opens and closes at the molecular level by developing a kinetic model to describe the behavior. The channel protein structure will be rationally mutated and the alterations in the function will be quantitatively assayed using electrophysiological methods. the preliminary results indicate that the opening of the KAT1 channel requires both hyperpolarization and some intracellular factors. The proposed research will identify the intracellular factors and investigate which amino acid residues of the channel involved in mediating the effects of these intracellular factors. The research proposed here will also investigate how the KAT1 channel opens in response to hyperpolarization. This research will examine if the structural and functional properties of the activation of the KAT1 channel favored by hyperpolarization are similar to those of the depolarization-activated potassium channels. By examining the molecular and biophysical properties to the KAT1 channel activated by hyperpolarization and by comparing the results with those obtained from depolarization-activated potassium channels, it should be possible to gain insights into the universal molecular principles involved in the voltage-dependent channel behavior. Furthermore, since the KAT1 channel is activated by the intracellular agonists and hyperpolarization, the results obtained will also be very relevant to the studies on various agonist-activated ion channels.

钾通道在生物系统中普遍发现并发挥作用 在细胞信号转导过程中的主要作用。 通常 通过夹紧膜电压来减少膜兴奋性 钾平衡电压。 功能特性 钾通道最终会影响生物体的反应方式 它的环境。 几个不同的钾通道已经 特征。 向内旋转钾通道响应 超极化，它们参与维持正常静止 潜在的。 通过影响静息潜力，这些内向晶状体 通道调节细胞兴奋性。 前面的例子，内心 肌肉，内向直线通道极大地影响了节奏性， 各种抗心律失常剂的有效性和动作电位 传导。 拟议的研究重点是克隆的向内促进剂钾 通道（KAT1）在异源表达系统中表达。 目标 这项研究的是了解该渠道如何打开和关闭 通过开发动力学模型来描述行为，分子水平。 通道蛋白结构将合理突变，并 该功能的更改将使用 电生理方法。 初步结果表明 KAT1通道的开放既需要超极化，又需要一些 细胞内因子。 拟议的研究将确定 细胞内因子并研究哪种氨基酸残基 介导这些细胞内因子的影响的通道。 这里提出的研究还将研究Kat1渠道如何 响应超极化而打开。 这项研究将检查是否 Kat1激活的结构和功能特性 超极化青睐的渠道与 去极化激活的钾通道。 通过检查Kat1通道的分子和生物物理特性 通过超极化激活，并将结果与​​这些结果进行比较 从去极化激活的钾通道获得 可以洞悉通用分子原理 参与电压依赖性通道行为。 此外，从那以后 KAT1通道被细胞内激动剂激活 超极化，获得的结果也将与 对各种激动剂激活的离子通道的研究。