STRUCTURAL STUDIES ON PROKARYOTIC POTASSIUM CHANNELS

电压依赖性离子通道有助于产生 膜电位、受体电位和动作电位。他们是 参与所有兴奋性的生理学和病理生理学 组织中 这些蛋白质是许多疾病过程的基础，包括 心律失常和癫痫，是基本药物的主要目标， 在临床医学中。 尽管有明显的生物学和临床 这些蛋白质的重要性，很少有人知道他们的 结构 获得这些结构信息是至关重要的 重要的是机械地理解它们的功能。 这一建议提出了一种解决结构问题的新方法， 这些蛋白质的功能。 将研究细菌模型系统 通过两种互补的技术：定点自旋标记和 电生理学 该研究将解决以下两个关键特性： 钾通道：渗透和门控。 人们认为 渗透和某种程度上的门控背后的结构要素 已被确认。 全阳离子选择性电压依赖性离子 通道共享一个共同的核心域，足以使离子 渗透 此外，一个非常不寻常的跨膜片段称为S4 被认为是导致 电压依赖性门控。 将对这两个结构要素进行研究 这两种技术。 预计自旋标记研究的结果将 提供足够的约束来确定这两个结构 元素到骨干褶皱的水平。 由此产生的折叠模型 将为一个机械启发的功能研究提供基础， 使用电生理学。 该提案的长期目标是 了解离子通道在结构水平上的功能特性。

Voltage-dependent ion channels are instrumental in the generation of membrane potential, receptor potential, and action potential. They are implicated in the physiology and pathophysiology of all excitable tissues. These proteins underlie many disease processes including arrhythmias and epilepsies and are major targets of essential drugs used in clinical medicine. Despite the obvious biological and clinical importance of these proteins, very little is known about their structure. Obtaining this structural information is of paramount importance to a mechanistic understanding of their function. This proposal presents a new approach toward addressing the structure and function of these proteins. Bacterial model systems will be studied by two complimentary techniques: site-directed spin labeling and electrophysiology. The study will address two key properties of potassium channels: permeation and gating. It is thought that the structural elements underlying permeation and, to some extent, gating have been identified. All cation selective voltage-dependent ion channels share a common core domain that is sufficient for ion permeation. Also, a highly unusual transmembrane segment known as S4 has been implicated as part of the structural element responsible for voltage-dependent gating. These two structural elements will be studied with the two techniques. It is anticipated that the results of the spin labeling study will provide sufficient constraints to determine the structure of these two elements to the level of the backbone fold. The resulting folding model will provide the basis for a mechanistically inspired functional study using electrophysiology. The long-term goal of this proposal is to understand functional properties of ion channels at a structural level.