STRUCTURAL CHANGE IN THE BETA SUBUNIT DURING GATING OF THE MUSCLE NICOTINIC RECEP

肌肉烟碱受体门控过程中 β 亚基的结构变化

• 批准号: 8130871
• 负责人: GUSTAV AKK
• 金额: $ 18.62万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8130871
• 关键词: Adult; Affect; Affinity; Agonist; Binding; Binding Sites; Biological; Coupling; Data; Energy Transfer; Environment; Equilibrium; Event; Extracellular Domain; Family; Gated Ion Channel; Ion Channel; Kinetics; Lateral; Lead; Mediating; Membrane; Membrane Proteins; Molecular; Molecular Conformation; Motion; Muscle; Mutation; Nature; Neuromuscular Junction; Nicotinic Receptors; Noise; Positioning Attribute; Process; Property; Proteins; Reaction; Receptor Activation; Relative (related person); Research; Research Design; Role; Shapes; Signal Transduction; Source; Synaptic Transmission; Time; Transmembrane Domain; Work; base; extracellular; insight; member; prototype; public health relevance; receptor; receptor binding; receptor function; research study

DESCRIPTION (provided by applicant): Members of the Cys-loop family of transmitter-gated ion channels are pentameric membrane proteins that respond to the binding of transmitter with a conformational change resulting in the opening of a gate and an increased affinity to the agonist. The muscle-type nicotinic acetylcholine receptor (nAChR) has served as a prototype in Cys-loop ion channel research due to its large single-channel conductance resulting in a high signal-to-noise ratio, and the relatively simple kinetic properties. In the nAChR, the two transmitter binding sites are located in the extracellular domain of the receptor at the interfaces between an a and a d subunit, and an a and an e. The subunit in the fifth position (b) is not directly involved in transmitter binding. The focus of this proposal is the non-transmitter-binding b subunit. We will use a combination of molecular biological, electrophysiological, and kinetic analyses approaches to determine the energetics and timing of gating motions in: i) the second membrane-spanning domain, ii) the extracellular region, and iii) the region comprising the linker between the second and third membrane-spanning regions and the pre-TM1 region. The work will elucidate the involvement of the b subunit in the conformational changes that lead to channel activation, and provide insight into the sources of molecular motions in the non- transmitter-binding subunit. The completion of the proposed work will increase our understanding of how transmitter-gated ion channels function, and how the non-transmitter-binding subunit shapes receptor function. PUBLIC HEALTH RELEVANCE: The nicotinic acetylcholine receptor mediates fast synaptic transmission in the vertebrate neuromuscular junction. The pentameric protein contains two transmitter binding sites located at subunit-subunit interfaces. This project is aimed at elucidating the role of the fifth subunit, which is not involved in transmitter binding, in the structural motions resulting in channel gating.

描述（由申请人提供）：递质门控离子通道的半胱环家族成员是五聚体膜蛋白，其响应递质的结合而发生构象变化，导致门打开并增加与激动剂的亲和力。肌肉型烟碱乙酰胆碱受体（nAChR）因其单通道电导大、信噪比高和相对简单的动力学特性而成为半胱环离子通道研究的原型。在 nAChR 中，两个递质结合位点位于受体的胞外域中 a 和 a d 亚基以及 a 和 e 之间的界面处。第五位 (b) 的亚基不直接参与递质结合。该提案的重点是非递质结合的 b 亚基。我们将结合使用分子生物学、电生理学和动力学分析方法来确定以下区域的门控运动的能量和时序：i) 第二跨膜结构域，ii) 细胞外区域，以及 iii) 包含第二和第三跨膜区域与前 TM1 区域之间的连接子的区域。这项工作将阐明 b 亚基参与导致通道激活的构象变化，并深入了解非递质结合亚基中分子运动的来源。完成拟议的工作将增加我们对递质门控离子通道如何发挥作用以及非递质结合亚基如何塑造受体功能的理解。 公众健康相关性：烟碱乙酰胆碱受体介导脊椎动物神经肌肉接头中的快速突触传递。五聚体蛋白含有两个位于亚基-亚基界面的递质结合位点。该项目旨在阐明第五个亚基（不参与递质结合）在导致通道门控的结构运动中的作用。