Structural Changes in BKCa Channels During Gating

超过空间Provioeo。大电导电压和Ca 2+激活的钾通道（BK）是一种膜蛋白，在控制平滑肌张力和神经元兴奋性方面起着重要作用。在大多数组织中，它们形成由成孔亚基和调节亚基组成的复合物。类似地，其他电压依赖性离子通道BK是主要由$4跨膜段代表的电压传感器。跨膜电位的变化使电压传感器移位，从而产生蛋白质的构象变化。最终，对于足够的去极化，随之而来的构象变化使通道进入允许离子传导的状态。关于调节BK通道开放和关闭的结构知之甚少，并且不存在关于由膜电位变化在BK通道中产生的动态重排的信息。本项目的目的之一是调查BK渠道运作背后的结构变化。通过对通道蛋白的残基特异性荧光标记来评估O_和13亚基的构象变化。短期目标是通过识别电压感知的运动区域，以及与激活、失活和失活相关的运动区域，以及参与其他通道功能的相对静止区域，来获得BK蛋白的更真实的视图。此外，还将研究孔区带电残基的作用。BK通道激活剂目前正在密切研究用于治疗尿失禁和作为中风神经保护剂。这项研究将有助于建立一个框架，设计新的治疗药物或改善已经通过的医疗实践。性能现场=

EXCEED THE SPACE PROVIOEO. Large conductance Voltage and Ca 2+ activated K¿ channels (BK) are membrane proteins that play a fundamental role in controlling smooth muscle tone and neuronal excitability. In most of the tissues, they form complexes composed by the pore-forming o_ subunit and by regulatory subunits. Similarly the other voltage dependent ion channels, BK posses a voltage sensor that is mainly represented by the $4 transmembrane segment. Changes in potential across the membrane displace the voltage sensor, producing a conformational change of the protein. Eventually, for adequate depolarizations, the consequent conformational change brings the channel into a state that allows ion conduction. Very little is known about structures that regulate the opening and closing of BK channels, and no information exists about the dynamical rearrangements produced in BK channels by changes in the membrane potential. One of the aims of this project is to investigate the structural changes underlying the operation of BK channel. Conformational changes of both o_ and 13subunits will be assessed by residue- specific fluorescent labeling of the channel protein. The short term objective is to obtain a more realistic view of BK protein by identifying regions of motion that underlie voltage sensing, and that are couple to activation, inactivation and deactivation, and regions of relative staticity, involved in other channel functions. In addition the role of charged residues in pore region will be investigated. BK channel activators are now under close investigation for treatment of urinary incontinence and as stroke neuroprotectant. This study will contribute to set a framework for the design of new therapeutic agents or for the amelioration of the one already adopted by the medical practice. PERFORMANCE SITE ========================================Section End===========================================