MECHANISMS OF PERMEATION IN INWARD RECTIFIER K+ CHANNELS

描述 （改编自申请人摘要）长期职业目标是进行 独立研究和在研究型大学任教。 目前，这是申请人作为助理教授的第一年， 宾夕法尼亚大学的生理学教授。 她的长期目标是 研究是为了了解能力的结构和功能基础 离子通道在各种细胞类型中完成其生物学任务。 在这个建议中，她将研究离子渗透的机制， 内向整流钾离子通道。 这些离子通道对 K+，并通过K+在向内的方向比在向外的更有效 方向 后一种性质被称为内向整流。 的 K+选择性和内向整流允许内向整流K+通道 调节许多细胞的静息膜电位， 完成他们的生物任务。 这里提出的实验的目的是 是研究这两种基本的 内向整流钾离子通道的离子渗透特性。 克隆的内向整流K+通道将在非洲爪蟾卵母细胞中表达， 将使用电生理学方法研究它们的渗透特性。 技术. 目的#1：研究的分子决定因素， 选择性K+结合位点。 申请人将采用综合方法： 在平衡条件下测量K+结合位点的占有率， 并诱变通道蛋白。 目标#2：调查 细胞内阻断离子引起的整流机制 处理以下问题：a.阻断离子抑制外向K+吗 通过占据K+结合位点来控制电流 B.外部K+是否缓解通道 通过静电机制被内部阻挡离子阻挡？ 这些研究具有重要的医学意义。 比如说， G蛋白门控内向整流钾通道介导心脏的调节 率迷走神经，ATP敏感性内向整流钾通道是 在心肌缺血中很重要。 (End摘要）

DESCRIPTION (Adapted from applicants' abstract) The long term career goal is to conduct independent research and to teach in a research-oriented university. Currently, this is the applicant's first year as an Assistant Professor of Physiology at the University of Pennsylvania. The long term goal of her research is to understand the structural and functional basis of the ability of ion channels to accomplish their biological tasks in various cell types. In this proposal, she will investigate the mechanisms of ion permeation in inward-rectifier K+ channels. These ion channels are highly selective for K+, and pass K+ in the inward direction more efficiently than in the outward direction. This latter property has been termed inward rectification. The K+ selectivity and inward rectification allow inward-rectifier K+ channels to regulate the resting membrane potential in many cells, through which they accomplish their biological tasks. The aim of the experiments proposed here is to investigate the molecular mechanisms underlying these two fundamental properties of ion permeation in inward-rectifier K+ channels. Cloned inward-rectifier K+ channels will be expressed in Xenopus oocytes and their permeation properties will be studied using electrophysiological techniques. Aim #1: To investigate the molecular determinants of the selective K+-binding site. The applicant will use a combined approach: measuring the occupancy of K+-binding sites under equilibrium conditions, and mutagenizing the channel protein. Aim #2: To investigate the mechanisms of the rectification induced by intracellular blocking ions by addressing the following questions: a. Do blocking ions inhibit outward K+ current by occupying a K+-binding site? b. Does external K+ relieve channel blockade by internal blocking ions through an electrostatic mechanism? The proposed studies have important medical implications. For example, G-protein gated inward-rectifier K+ channels mediate the regulation of heart rate by vagal nerve, and ATP-sensitive inward-rectifier K+ channels are important during cardiac ischemia. (End of Abstract)