Nicotinic Acetylcholine Receptor Structure, Thermal Motion and Gating

本课题旨在研究肌肉烟碱乙酰胆碱受体（nAChR）的结构及其在通道激活过程中的构象变化。烟碱性乙酰胆碱受体介导神经-肌肉连接处和大脑中的快速突触传递。最近发表的ACh结合蛋白（AChBP）和Torpedo AChR结构的研究，使人们对AChR的三维结构有了新的认识，并为以下具体目标提供了基础：1)通过确定特定跨膜段残基之间的接近关系，测试4-A分辨率AChR跨膜结构域模型的有效性。2)确定M2通道衬里段在静息和激活状态下的热迁移率。3)绘制激活过程中跨膜结构域的结构变化。4)探测参与配体结合到通道门控转导的M2-M3环周围的蛋白质包装。结果将验证从4-A分辨率数据推断的结构信息。此外，它们还将用于改进受体的结构模型。这将允许更详细地研究变构配体的结合位点，从而允许设计改进的药物，此外，本研究将阐明动态事件，如热和门控诱导运动。

This research project aims at studying the muscle nicotinic acetylcholine receptor (nAChR) structure and the conformational changes it undergoes during channel activation. Nicotinic AChR mediate fast synaptic transmission at the nerve-muscle junction and in the brain. The recent publication of the ACh binding protein (AChBP) and Torpedo AChR structures has allowed new insights into the three dimensional structure and provides the basis for the following Specific Aims: 1) To test the validity of the 4-A resolution AChR transmembrane domain model by determining proximity relationships between specific transmembrane segment residues. 2) To determine the thermal mobility of the M2 channel-lining segments in the resting and activated states. 3) To map structural changes in the transmembrane domain during activation. 4) To probe protein packing around the M2-M3 loop that is involved in the transduction of ligand binding to channel gating. The results will validate the structural information inferred from the 4-A resolution data. In addition they will be used to refine the structural model of the receptor. This will allow more detailed investigations of binding sites for allosteric ligands, thus allowing design of Improved drugs, in addition, this study will elucidate dynamic events such as thermal and gating-induced movements.