Investigation of the Mg2+ Blockade of the NMDA Receptor

描述(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，其逻辑门功能位于记忆形成分子过程的核心。在静止膜电位下，仅有谷氨酸配体的存在不足以打开通道，因为通道的孔被镁离子堵塞。神经元的去极化消除了这种障碍，允许钙流动，启动突触的加强和记忆的形成。通过NMDAR的过度钙流动被认为是缺血、中风和几种神经疾病的神经退行性变的基础。药物治疗必须能够使这种基本蛋白质的功能恢复正常。这类药物的开发需要详细了解NMDAR的微妙之处。NMDAR阻断位点的不同寻常之处在于它是疏水性的，而不是像大多数镁离子结合位点那样带有高度负电荷。我们希望通过结合非天然氨基酸，对蛋白质结构进行一系列微妙而戏剧性的改变，从而剖析镁离子的阻断。我们将通过电生理学对这些空间和电子相互作用与镁离子相互作用的化学微扰进行功能分析。

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.