Subunit assembly of N-methyl-d-aspartate receptors analyzed by fluorescence resonance energy transfer
Subunit assembly of N-methyl-d-aspartate receptors analyzed by fluorescence resonance energy transfer
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DOI：
10.1074/jbc.m413915200
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发表时间：
2005-07-01
影响因子：
4.8
通讯作者：
Luo, JH
中科院分区：
文献类型：
--
作者：
Qiu, S;Hua, YL;Luo, JH
N-甲基-D-天冬氨酸（NMDA）受体在突触传递和可塑性以及兴奋性毒性中起重要作用。NMDA受体被认为是主要由NMDA受体（NR）1和NR 2亚基组成的四聚体复合物。NR 1亚基是形成功能性NMDA受体通道所必需的，而NR 2亚基修饰通道特性。生化和功能研究表明，组成NMDA受体的亚基被组织成二聚体的二聚体，并且亚基的N末端是受体组装的主要决定因素。在这里，我们使用了生物物理的方法，荧光共振能量转移，分析完整的，功能性NMDA受体在活细胞中的组装。结果表明，NR 1、NR 2A和NR 2B亚基在HEK 293细胞中单独表达时可形成同源二聚体。在NR 1和NR 2亚基之间形成的异聚体NMDA受体中也存在亚基同源二聚体。这些发现与功能性NMDA受体被排列为二聚体的二聚体一致。此外，我们的数据表明，NR 1亚基同源二聚体的构象的影响，在形成异聚体受体复合物的合作伙伴NR 2亚基，这可能是基础的机制，NR 2亚基修饰NMDA受体功能。
N-methyl-D-aspartate (NMDA) receptors play major roles in synaptic transmission and plasticity, as well as excitotoxicity. NMDA receptors are thought to be tetrameric complexes mainly composed of NMDA receptor (NR)1 and NR2 subunits. The NR1 subunits are required for the formation of functional NMDA receptor channels, whereas the NR2 subunits modify channel properties. Biochemical and functional studies indicate that subunits making up NMDA receptors are organized into a dimer of dimers, and the N termini of the subunits are major determinants for receptor assembling. Here we used a biophysical approach, fluorescence resonance energy transfer, to analyze the assembly of intact, functional NMDA receptors in living cells. The results showed that NR1, NR2A, and NR2B subunits could form homodimers when they were expressed alone in HEK293 cells. Subunit homodimers were also found existing in heteromeric NMDA receptors formed between NR1 and NR2 subunits. These findings are consistent with functional NMDA receptors being arranged as a dimer of dimers. In addition, our data indicated that the conformation of NR1 subunit homodimers was affected by the partner NR2 subunits during the formation of heteromeric receptor complexes, which might underlie the mechanism by which NR2 subunits modify NMDA receptor function.