Investigation of the Mg2+ Blockade of the NMDA Receptor

描述（由申请人提供）：N-甲基-D-天冬氨酸受体（NMDAR）是一种配体门控离子通道蛋白，其作为逻辑门的功能位于记忆形成的分子过程的核心。在静息膜电位下，单独存在谷氨酸配体不足以打开通道，因为其孔被Mg 2+阻断。神经元的去极化消除了阻滞，允许钙流动，从而启动突触和记忆形成的加强。通过NMDAR的过量钙流被认为是缺血、中风和几种神经系统疾病中的神经变性的基础。药物治疗必须能够调整这种必需蛋白质的功能恢复正常。这些药物的开发需要详细了解NMDAR的微妙之处。NMDAR阻断位点是不寻常的，因为它是疏水性的，而不是像大多数Mg 2+结合位点那样带高度负电荷。我们希望通过非天然氨基酸的位点特异性掺入，使用一系列对蛋白质结构的微妙和戏剧性的改变来剖析Mg 2+阻断。我们将通过电生理学功能分析这些化学扰动的空间和电子相互作用的镁离子。

DESCRIPTION (provided by applicant): The N-methyl-D-aspartate receptor (NMDAR) is a ligand-gated ion channel protein whose function as a logic gate lies at the heart of the molecular processes of memory formation. At resting membrane potentials the presence of the glutamate ligand alone is insufficient to open the channel because its pore is blocked by Mg2+. Depolarization of the neuron removes the blockade, permitting calcium flow that initiates a strengthening of the synapse and memory formation. Excessive calcium flow through the NMDAR is believed to underlie neurodegeneration in ischemia, stroke, and several neurological diseases. Drug treatments must be able to tweak this essential protein's function back to normal. The development of such drugs requires a detailed understanding of the subtleties of the NMDAR. The NMDAR blockade site is unusual in that it is hydrophobic, rather than highly negatively charged, like most Mg2+-binding sites. We hope to dissect the Mg2+ blockade using a series of subtle and dramatic alterations to the protein structure through the site-specific incorporation of unnatural amino acids. We will functionally assay these chemical perturbations of the steric and electronic interactions with the Mg2+ cation through electrophysiology.