Transmembrane Region of N-Methyl-D-aspartate Receptor (NMDAR) Subunit Is Required for Receptor Subunit Assembly
Transmembrane Region of N-Methyl-D-aspartate Receptor (NMDAR) Subunit Is Required for Receptor Subunit Assembly
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N-甲基-D-天冬氨酸受体 (NMDAR) 亚基的跨膜区域是受体亚基组装所必需的
DOI：
10.1074/jbc.m111.235333
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发表时间：
2011-08-05
影响因子：
4.8
通讯作者：
Luo, Jian-hong
中科院分区：
文献类型：
--
作者：
Cao, Jing-yuan;Qiu, Shuang;Luo, Jian-hong
N-甲基-D-天冬氨酸受体(NMDAR)是谷氨酸三大类离子受体之一，在突触可塑性、突触发生和兴奋性毒性中发挥重要作用。与非NMDA受体不同，NMDAR被认为是由主要由GluN1和GluN2亚基组成的必需的异四聚体复合体。当在异种细胞中单独表达时，如HEK293细胞，由于内质网信号的滞留，大多数NMDAR亚单位既不能离开内质网，也不能在细胞膜上表达。只有当NMDAR异构化组装时，内质网滞留信号才能被屏蔽，NMDAR才能在表膜上表达。然而，NMDAR组装的机制仍然知之甚少。为了确定亚基中介导这种组装的区域，我们制作了一系列截短或嵌合的cDNA构建物。利用活细胞中的FRET测量，结合免疫染色和免疫共沉淀分析，我们检测了NMDAR亚单位的组装决定域。我们的结果表明，NMDAR亚基的跨膜区是组装NMDAR亚基所必需的，无论是同源二聚体还是异构体。
N-Methyl-D-aspartate receptors (NMDARs), one of three main classes of ionotropic glutamate receptors, play major roles in synaptic plasticity, synaptogenesis, and excitotoxicity. Unlike non-NMDA receptors, NMDARs are thought to comprise obligatory heterotetrameric complexes mainly composed of GluN1 and GluN2 subunits. When expressed alone in heterogenous cells, such as HEK293 cells, most of the NMDAR subunits can neither leave the endoplasmic reticulum (ER) nor be expressed in the cell membrane because of the ER retention signals. Only when NMDARs are heteromerically assembled can the ER retention signals be masked and NMDARs be expressed in the surface membrane. However, the mechanisms underlying NMDAR assembly remain poorly understood. To identify regions in subunits that mediate this assembly, we made a series of truncated or chimeric cDNA constructs. Using FRET measurement in living cells combined with immunostaining and coimmunoprecipitation analysis, we examined the assembly-determining domains of NMDAR subunits. Our results indicate that the transmembrane region of subunits is necessary for the assembly of NMDAR subunits, both for the homodimer and the heteromer.