Desensitization of Nicotinic Acetylcholine Receptors

烟碱乙酰胆碱受体的脱敏

• 批准号: 9378463
• 负责人: Anthony L Auerbach
• 金额: $ 31.63万
• 依托单位: STATE UNIVERSITY OF NEW YORK AT BUFFALO
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9378463
• 关键词: Agonist; Amino Acids; Binding; Binding Sites; Cells; Cholinergic Receptors; Coupling; Equilibrium; Event; Free Energy; Gated Ion Channel; Global Change; Goals; Hydrophobicity; Investigation; Ion Channel; Ion Channel Gating; Knowledge; Ligands; Location; Measures; Membrane Proteins; Methods; Microscopic; Molecular; Molecular Conformation; Muscle; Mutation; Nerve; Neurotransmitter Receptor; Neurotransmitters; Nicotinic Receptors; Pathway interactions; Pattern; Pharmacology; Physiological; Positioning Attribute; Potential Energy; Probability; Process; Proline; Recovery; Refractory; Speed; Structure; Surface; Synapses; Synaptic Receptors; Testing; Transmembrane Domain; desensitization; experimental study; interest; mutant; operation; prevent; receptor; response; voltage

Nicotinic acetylcholine receptors (AChRs) at the nerve-muscle synapse enter and recover from D(esensitized) states that remain inactive in the continuous presence of neurotransmitter. Receptor desensitization down-regulates cell responses and encodes long-term activity patterns. Our goal is to understand the AChR desensitization process at a molecular level. The essential problem of how D states are connected to C(losed) and O(pen) gating states remains unsolved. We will investigate two hypotheses: i) D, O and C are connected in a closed cycle and ii) D is not connected either to C or O but rather to a short-lived gating intermediate state. We will test the second hypothesis experimentally by using mutations and voltage to shift the point of bifurcation between gating and desensitization conformational-change pathways, towards C to produce openings upon recovery or towards O to prevent openings. Many amino acids change structure during the AChR gating and desensitization transitions, and each of these microscopic rearrangements has an associated and mostly-local free energy change. We will measure these energy changes in desensitization at two regions in the AChR transmembrane domain: i) a proline kink in M1 and ii) the hydrophobic M2 gate. Despite intensive investigation, the molecular basis of AChR desensitization has remained obscure since the process was first described 60 years ago. The experiments in this proposal will fill this substantial gap in our understanding of receptor operation.

神经肌肉突触处的烟碱乙酰胆碱受体 (AChR) 进入并恢复 D（增敏）状态在神经递质持续存在的情况下保持不活动状态。 受体脱敏下调细胞反应并编码长期活动模式。 我们的目标是在分子水平上了解 AChR 脱敏过程。必不可少的 D 状态如何连接到 C(losed) 和 O(pen) 门控状态的问题仍未解决。 我们将研究两个假设：i) D、O 和 C 在闭环中相连，ii) D 不是 连接到 C 或 O，而是连接到短暂的门控中间态。我们将测试 第二个假设通过实验使用突变和电压来移动点 门控和脱敏构象变化途径之间的分歧，朝向 C 至 恢复时产生开口或朝向 O 以防止开口。许多氨基酸发生变化 乙酰胆碱受体门控和脱敏转变期间的结构，以及这些微观的每一个 重排具有相关且主要是局部的自由能变化。我们将测量这些 AChR 跨膜域中两个区域脱敏的能量变化： i) a M1 中的脯氨酸扭结和 ii) 疏水性 M2 门。尽管进行了深入调查， 自从该过程首次出现以来，AChR 脱敏的分子基础仍然不清楚 60年前描述的。本提案中的实验将填补我们的这一巨大空白 了解受体的运作。