Structure, function and dynamics of a glutamate receptor

离子型谷氨酸受体控制多种正常的神经元过程， 记忆此外，这些重要的神经递质受体的激活参与了许多神经递质受体的激活。 神经退行性疾病，特别是中风和癫痫。因此，针对谷氨酸的药物 受体将具有相当大的治疗价值。跨膜拓扑结构的分析导致了 认识到每个亚基由一系列模块组成，并且结合谷氨酸的模块可以是 在细菌中作为可溶性蛋白（S1 S2结构域）产生。S1 S2结构域结合激动剂， 拮抗剂具有与完整受体大致相同的亲和力，并作为一个优秀的系统 来研究结合域。GluR 2亚基的S1 S2结构域的晶体结构已被证实。 解决了E. Gouaux和合作者。我们已经使用NMR光谱来表征动态 GluR 2 S1 S2结构域的性质。不幸的是，GluR 2受体的功能很难研究 这是由于其快速的动力学和低的沟道电导。这项建议的目的是扩大 结构和动力学研究谷氨酸受体亚单位（GluRS），形成通道更适合 进行详细的动力学测量。NMR和荧光研究将表征结构， 在一系列完全和部分激动剂的存在下的动力学。如晶体结构和 同源性模型，S1 S2结构域是一个双叶结构，在配体结合时关闭。我们的假设 通道传导受单个亚基中叶闭合的调节， 尺度构象动力学或叶内动力学有助于电导水平的变化。 开放通道爆发中的开放和关闭与开放通道的内部动力学处于相同的时间尺度上。 S1 S2结构域。将测定同聚GluRS的单通道电导和速率常数 受体通道在同一系列的激动剂，以确定是否有明确的差异，在原子水平的相互作用 激动剂和受体构象之间的差异影响通道动力学。内部比较 具有通道的单通道特性的动态应该允许我们确定这些动态是否 在控制离子通道功能中发挥作用。最后一个目标将包括核磁共振和单通道记录 以确定叶间界面在激动剂亲和力控制中的作用 和功效。虽然同聚体GLURS受体通道可能局限于少数的 在神经元中，GLUR 2/GLUR 3异聚体受体通道可能代表了大量的 突触后的AMPA受体。这些结果将有助于阐明 重要谷氨酸受体亚单位，并为进一步药物开发提供必要信息。

lonotropic glutamate receptors control a variety of normal neuronal processes including learning and memory. In addition, activation of these important neurotransmitter receptors is involved in a number of neurodegenerative diseases, notably stroke and epilepsy. Thus, drugs targeted toward glutamate receptors would be of considerable therapeutic value. Analysis of the transmembrane topology led to the realization that each subunit is made of a series of modules, and the module that binds glutamate can be produced in bacteria as a soluble protein (S1S2 domain). The S1S2 domain binds agonists and antagonists with approximately the same affinity as the intact receptor and serves as an excellent system for studying the binding domain. The crystal structure of the S1S2 domain of the GluR2 subunit has been solved by E. Gouaux and collaborators. We have used NMR spectroscopy to characterize the dynamic properties of the GluR2 S1S2 domain. Unfortunately, the function of the GluR2 receptor is difficult to study due to its rapid kinetics and low channel conductance. The purpose of this proposal is to extend the structural and dynamic studies to a glutamate receptor subunit (GluRS) that forms channels more suitable for detailed kinetic measurements. NMR and fluorescence studies will characterize the structure and dynamics in the presence of a series of full and partial agonists. As shown by crystal structures and homology models, the S1S2 domain is a bilobe structure that closes upon ligand binding. Our hypothesis is that the channel conductance is modulated by lobe closure in individual subunits and that either large- scale conformational dynamics or intralobe dynamics contribute to changes in conductance levels. Openings and closings within an open channel burst are on the same timescale as the internal dynamics of the S1S2 domain. Single channel conductances and rate constants will be determined for homomeric GluRS receptor-channels in the same series of agonists to determine if clear differences in atomic level interactions between agonist and receptor conformation differentially affect channel kinetics. Comparison of the internal dynamics with the single channel properties of the channels should allow us to determine if these dynamics play a role in the control of ion channel function. The last aim will include NMR and single channel recordings from mutated S1S2 domains to determine the role of the interlobe interface in the control of agonist affinity and efficacy. Although homomeric GLURSreceptor-channels are likely to be confined to a small number of neurons, GLUR2/GLUR3 heteromeric receptor-channels may represent a significant number of postsynaptic AMPA receptors in the neocortex. The results will shed light on the binding site of an important glutamate receptor subunit and provide essential information for further drug development.