Voltage Gating Mechanisms

 描述(由申请人提供)：电压门控离子通道已经进化为响应膜电位的变化而打开和关闭，并选择性地快速传导离子。分离时间最长的家族成员是电压门控质子通道Hv1及其相对亲缘的电压敏感磷酸酶(VSP)。人类免疫缺陷病毒1在先天免疫和其他生理过程中起着核心作用。VSP的生物学功能尚不清楚。这一建议关注于这些VSD蛋白功能的三个基本方面，尽管它们相似，但它们的效应器却有根本的不同：Hv1具有唯一位于其VSD内的通道效应器，而VSP的效应器是迄今为止唯一一个将其效应器置于膜外的效应器，在这种情况下位于内侧。我们对Hv1的研究目的是阐明它的孔道，了解它是如何“门控”的，一个亚基中的门控装置如何影响二聚体伙伴的门控装置，并阐明Hv1检测pH的绝对跨膜梯度并利用它来调节门控的机制。我们研究VSP的目的是了解VSD中的构象序列如何诱导酶结构域中的构象序列改变底物的选择。我们的目标是得到门控、协作性和VSD受pH和效应器VSD调制的机制分子模型。建议的研究应该有助于深入了解电压门控蛋白中VSD的功能，新的方法应该适用于其他一系列通道和受体，这些通道和受体的蛋白质运动、亚单位相互作用和配体的调节都是感兴趣的。这项拟议的工作旨在阐明电压门控质子通道(它是先天免疫、生殖和上皮运输的基础，似乎在中风和癌症中起作用)及其相关的电压敏感磷酸酶的功能机制。该方法使用了几种新的光学方法，应该被证明适用于对广泛的离子通道和受体的研究。

 DESCRIPTION (provided by applicant): Voltage-gated ion channels have evolved to open and close in response to changes in the membrane potential and rapidly conduct ions selectively. The members of the family that longest eluded isolation were the voltage-gated proton channel, Hv1, and its relatively close relative, the voltage sensing phosphatase (VSP). Hv1 plays a central role in innate immunity and other physiological processes. The biological function of VSP is not known. This proposal focuses on 3 fundamental aspects to the function of these VSD proteins, which, despite their similarities, differ radically in their effectors: with Hv1 having is channel effector uniquely situated within its VSD, while VSP's effector is the only one so far to have its effector outside of the membrane, in this case on the internal side. Our aims for Hv1 are to elucidate its pore pathway, understand how it is "gated", how the gating apparatus in one subunit influences that of the dimeric partner and elucidate the mechanism by which Hv1 detects the absolute transmembrane gradient of pH and uses it to regulate gating. Our aim for VSP is to understand how conformational sequences in the VSD induce conformational sequences in the enzyme domain to alter the choice of substrate. Our goal is to arrive at mechanistic molecular models of gating, cooperativity and modulation of the VSD by pH and modulation by the VSD of the effector. The proposed studies should provide insight into the function of VSDs across voltage-gated proteins and the new methods should be applicable to a range of other channels and receptors whose protein motions, subunit interactions and modulation by ligands are of interest. The proposed work is designed to elucidate the mechanism of function of the voltage-gated proton channel (which is fundamental to innate immunity, reproduction and epithelial transport, and appears to have a role in stroke and cancer) and its relative, the voltage sensing phosphatase. The approach employs several novel optical methods that should prove to be applicable to the study of a broad set of ion channels and receptors.