MOLECULAR ASPECTS OF VOLTAGE ACTIVATION IN ION CHANNELS

本提案的长期目标是深入了解电压 依赖性离子通道以分子形式起作用，并定义 与跨膜相关的不同蛋白质构象变化 电压变化和通道选通。 离子电流和门控电流 将被衡量。 门控电流是 电压传感器的运动。 这些实验是为了 克隆的K通道。 两个主要的初步调查结果是关键方面， 本建议：1.电荷早期峰值分量的发现 运动记录在高带宽（200千赫）和2。的趋势 门控电流率饱和在极端电位。 早期 门控电流分量和随电压饱和的趋势 率是一致的看法，该通道过境大量 像电荷沿着一个能量的扩散过程 由栅栏和威尔斯构成的景观。 具体目标是：1.到 研究门控电流的早期分量。 ON和OFF选通 电流之前有一个快速组件。 2.探讨 门控电流率饱和趋势的潜在机制 有电压。 选通电流率在高时趋于饱和， 潜力 电荷沿着能量扩散的模型 将测试用屏障和威尔斯形成的景观。 3.获得 通过门控电流的表征了解通道功能 噪声和定义所涉及的带电残基。的性质 将研究选通噪声。 4.研究机制 通过离子和门控电流表征的缓慢灭活 长时间去极化期间的性能。 我们将检验这个假设 有两种类型的慢失活和5.为了获得 基于离子和门控电流的Shaker K通道功能整体模型 数据这些确定与门控电流噪声一起 测量，应该为预测提供明确的约束条件 在通道门控期间发生的构象变化。 这 离子通道的基本性质的研究， 设计和测试治疗药物。

The long term goals of this proposal are to gain insight on how voltage dependent ion channels function in molecular terms, and to define the different protein conformational changes associated with transmembrane voltage changes and channel gating. Ionic currents and gating currents will be measured. The gating currents are the electrical manifestation of the movement of the voltage sensor. The experiments are planned for cloned K channels. Two main preliminary findings are key aspects of this proposal: 1. the discovery of an early peak component of charge movement recorded at high bandwidth (200 kHz) and 2. a tendency of gating current rates to saturate at extreme potentials. The early component and the tendency to saturation with voltage of gating current rates are consistent with the view the channel transits a large number of states, like in a diffusion process of the charge along an energy landscape shaped with barriers and wells. The specific aims are: 1. To investigate the early component of gating currents. ON and OFF gating currents were preceded by a fast component. 2. To investigate the mechanism underlying the tendency of gating current rates to saturate with voltage. The gating current rates tend to saturate at high potentials. A model in which the charge diffuses along an energy landscape shaped with barriers and wells will be tested. 3. To gain insight on channel function via a characterization of the gating current noise and to define the charged residues involved. The properties of gating noise will be investigated. 4. To investigate mechanism(s) of slow inactivation by a characterization of ionic and gating current properties during long depolarizations. We will test the hypothesis that there are two types of slow inactivation and 5. To obtain a global model of Shaker K channel function from ionic and gating current data. These determinations, in conjunction with gating current noise measurements, should provide well defined constraints for the prediction of the conformational changes occurring during channel gating. This research on fundamental properties of ion channel should be valuable to the design and test therapeutic drugs.