MODULATION OF KV CHANNEL BY AN ASSOCIATED BETA SUBUNIT

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 电压依赖性钾通道(Kv)控制K+在细胞膜上的流动，以响应膜电位的变化。Kv通道的开放可引起膜超极化，从而抑制膜的过度兴奋性或简单地降低膜的正常活性。Kv通道是神经传导、肌肉收缩和激素分泌等许多基本生物学过程的中枢。在细胞中，Kv通道总是与许多其他蛋白质结合形成大分子复合体，相关蛋白调节通道功能。我们研究的长期目标是发展对通道调制机制的原子水平的理解。在本项目中，我们主要研究β亚基对Kv通道的调制作用。我们发现，β亚基是一种利用NADPH辅因子催化氧化还原反应的氧化还原酶。我们还发现，与NADPH(还原的)或NADP+(氧化的)结合的β亚基对通道功能的调制不同。我们将解决β亚基与整个钾通道和细胞内通道结构域的复合体的高分辨率结构，包括还原和氧化两种形式。我们还将解决与小分子调节剂的复合体中影响通道功能的β亚基的结构。钾电流的急剧变化在各种细胞中观察到，在启动细胞对低氧条件和氧化应激的反应中是必不可少的，但机制通常不清楚。β亚基可能在细胞内氧化还原化学与通道活动的偶联中发挥重要作用。我们的研究将解决这一可能性，并导致阐明β亚基？S在细胞中的生理作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Voltage-dependent potassium channels (Kv) control the flow of K+ through the cell membrane in response to changes in membrane potential. The opening of Kv channels causes membrane hyperpolarization that can curtail excessive membrane excitability or simply tone down normal membrane activity. Kv channels are central to many fundamental biological processes, such as nerve conduction, muscle contraction, and hormone secretion.In a cell, Kv channels are always associated with many other proteins to form a macromolecular complex, and the associated proteins modulate channel functions. The long-term goal of our research is to develop an atomic level understanding of channel modulation mechanisms. In this project, we focus on modulation of Kv channel by beta subunit. We have found that beta subunit is an oxidoreductase that utilizes an NADPH cofactor to catalyze a redox reaction. We also found that beta subunit bound with an NADPH (reduced) or an NADP+ (oxidized) modulates channel function differently. We will solve high resolution structures of the beta subunit in complex with the whole potassium channel and with intracellular channel domains, in both reduced and in oxidized forms. We will also solve structures of the beta subunit in complex with small molecule modulators that affect channel functions.Acute changes in potassium current are observed in a variety of cells and are essential in initiating cellular responses to hypoxic conditions and oxidative stresses, but the mechanisms are often unknown. Beta subunit may play an important role in coupling intracellular redox chemistry to channel activities. Our study will address this possibility and lead to the elucidation of beta subunit¿??s physiological role in a cell.