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Cys-loop家族成员是五聚体膜蛋白，它们对递质结合做出反应，产生构象变化，导致门的打开和对激动剂的亲和力增加。肌肉型尼古丁乙酰胆碱受体（nictinicacetylcholine receptor, nAChR）因其单通道电导大，信噪比高，且动力学性质相对简单，成为Cys-loop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结构域，位于a和d亚基以及a和e之间的界面。位于第5个位置(b)的亚基不直接参与递质结合。本提案的重点是非传递体结合的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门控运动的能量学和时间：i)第二跨膜区域，ii)细胞外区域，以及iii)包含第二和第三跨膜区域与前tm1区域之间连接的区域。这项工作将阐明b亚基参与导致通道激活的构象变化，并提供对非递质结合亚基分子运动来源的见解。这项工作的完成将增加我们对递质门控离子通道功能的理解，以及非递质结合亚基如何塑造受体功能。