Oxidoreductase Activity of the Beta Subunit of Kv Channels

Kv 通道 β 亚基的氧化还原酶活性

• 批准号: 7386484
• 负责人: Oleg A Barski
• 金额: $ 18.5万
• 依托单位: UNIVERSITY OF LOUISVILLE
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-01-15 至 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7386484
• 关键词: Action Potentials; Affinity; Apoptosis; Arrhythmia; Binding; Biochemical; COS-7 Cell; Catalysis; Cell Volumes; Cells; Clinical; Complex; Cytoplasmic Tail; Dependence; Depth; Epilepsy; Foundations; Goals; Immune System Diseases; Investigation; Isotopes; Kinetics; Lead; Learning; Learning Disabilities; Ligand Binding; Lipid Peroxidation; Measures; Mediating; Membrane Potentials; Memory; Metabolic; Metabolism; Neurotransmitters; Nucleotides; Oxidation-Reduction; Oxidoreductase; Oxygen; Patch-Clamp Techniques; Physiological; Play; Potassium; Potassium Channel; Property; Prostaglandins; Proteins; Pulmonary Hypertension; Rate; Reaction; Reagent; Regulation; Research; Rest; Role; Sequence Analysis; Series; Steroids; Surface; System; Testing; analog; base; carbonyl reductase (NADPH); in vivo; member; memory encoding; novel; porin; pyridine nucleotide; research study; voltage

DESCRIPTION (provided by applicant): The overall goal of this project is to define the catalytic properties of the ¿-subunit of the voltage-sensitive potassium channel (Kv). The Kv channels regulate cell excitability and have been shown to play an important role in oxygen-sensing, volume regulation, memory, and learning. The Kv¿ proteins are ancillary proteins that associate with the cytoplasmic domain of Kv channels, but no clear physiological function has been assigned to these proteins. Structural and sequence analyses show that Kv¿ proteins are members of the aldo-keto reductase superfamily. Our central hypothesis is that the Kv¿ proteins catalyze the reduction of endogenous carbonyls whereby they impart redox sensitivity to Kv currents. Such regulation may be an important feature of oxygen-sensing or metabolic dependence of Kv currents. To test this hypothesis we will measure the catalytic efficiency of Kv¿ proteins with endogenous substrate series consisting of prostaglandins, steroids, metabolites of neurotransmitters and lipid peroxidation products. We will also test whether assembly of Kva-¿ complexes enhance enzymatic activity of Kv¿ and determine the sequence and rate-limiting step in its catalytic cycle (Aim 1). To determine whether the endogenous carbonyls utilized by Kv¿ in biochemical experiments, are also functionally active, we will examine the ability of the most efficient series to alter the voltage-sensitivity and the kinetics of Kva-¿ channels expressed in COS-7 cells (Aim 2). Results of these experiments will allow us to distinguish whether nucleotide binding itself, catalytic cycle, or binding of ligands which can serve as pharmacologic agents modulate Kv inactivation. Taken together, the findings of this study will provide a better understanding of the catalytic and ligand binding properties of Kv¿ and form the basis of a more in-depth project to examine the in vivo role of Kv¿ catalysis and its putative role in regulating surface excitability, oxygen-sensing, or encoding memory. Results of these studies could also form the basis of developing pharmacological modulators of Kv¿-mediated changes in Kv current.

描述（由申请人提供）：该项目的总体目标是定义电压敏感钾通道（Kv）的β亚基的催化特性。 Kv 通道调节细胞兴奋性，并已被证明在氧感应、容量调节、记忆和学习中发挥重要作用。 Kv¿ 蛋白是与 Kv 通道的细胞质结构域相关的辅助蛋白，但尚未为这些蛋白指定明确的生理功能。结构和序列分析表明 Kv¿ 蛋白是醛酮还原酶超家族的成员。我们的中心假设是 Kv¿ 蛋白催化内源羰基的还原，从而赋予 Kv 电流氧化还原敏感性。这种调节可能是 Kv 电流的氧传感或代谢依​​赖性的一个重要特征。为了检验这一假设，我们将测量 Kv¿ 蛋白与由前列腺素、类固醇、神经递质代谢物和脂质过氧化产物组成的内源底物系列的催化效率。我们还将测试 Kva-¿ 复合物的组装是否增强 Kv¿ 的酶活性，并确定其催化循环中的序列和限速步骤（目标 1）。为了确定 Kv¿ 在生化实验中利用的内源羰基是否也具有功能活性，我们将检查最有效的系列改变 COS-7 细胞中表达的 Kva-¿ 通道的电压敏感性和动力学的能力（目标 2）。这些实验的结果将使我们能够区分核苷酸结合本身、催化循环还是可以作为药理学试剂调节 Kv 失活的配体结合。总而言之，这项研究的结果将有助于更好地理解 Kv¿ 的催化和配体结合特性，并构成更深入项目的基础，以检查 Kv¿ 催化的体内作用及其在调节表面兴奋性、氧感应或编码记忆中的假定作用。这些研究的结果也可以构成开发 Kv 介导的 Kv 电流变化的药理学调节剂的基础。