Stationary Gating of GluN1/GluN2B Receptors in Intact Membrane Patches
Stationary Gating of GluN1/GluN2B Receptors in Intact Membrane Patches
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DOI：
10.1016/j.bpj.2009.12.4276
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发表时间：
2010-04-07
影响因子：
3.4
通讯作者：
Popescu, Gabriela K.
中科院分区：
文献类型：
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作者：
Amico-Ruvio, Stacy A.;Popescu, Gabriela K.
NMDA受体是由GluN 1和GluN 2亚基组成的异聚谷氨酸门控通道。GluN 2亚基类型（A-D）不同的受体亚型在整个中枢神经系统中表达差异，并在重组系统中具有不同的动力学特性。具体的受体亚型如何促进通常归因于NMDA受体的功能仍然未知，部分原因是单个受体类型的功能表征不完整和天然受体的分子组成不清楚。我们研究了单个大鼠重组GluN 1/GluN 2B受体在瞬时转染HEK 293细胞的细胞贴附补丁中的静态门控动力学，并使用动力学分析和建模来描述该受体的门控行为的全方位。我们发现，像GluN 1/GluN 2A受体，GluN 1/GluN 2B受体有三个门控模式，可区分其平均开放时间。然而，对于GluN 1/GluN 2B受体，模式也显着不同的平均关闭持续时间，从而产生了更广泛的开放概率。我们还发现，无论门控模式，谷氨酸解离发生类似的4倍更慢（k = 15 s（-1））相比，在GluN 1/GluN 2A受体观察到。在这些结果的基础上，我们认为，缓慢的谷氨酸解离和模式门控的基础上长的异质性激活的GluN 1/GluN 2B受体。
NMDA receptors are heteromeric glutamate-gated channels composed of GluN1 and GluN2 subunits. Receptor isoforms that differ in their GluN2-subunit type (A-D) are expressed differentially throughout the central nervous system and have distinct kinetic properties in recombinant systems. How specific receptor isoforms contribute to the functions generally attributed to NMDA receptors remains unknown, due in part to the incomplete functional characterization of individual receptor types and unclear molecular composition of native receptors. We examined the stationary gating kinetics of individual rat recombinant GluN1/GluN2B receptors in cell-attached patches of transiently transfected HEK293 cells and used kinetic analyses and modeling to describe the full range of this receptor's gating behaviors. We found that, like GluN1/GluN2A receptors, GluN1/GluN2B receptors have three gating modes that are distinguishable by their mean open durations. However, for GluN1/GluN2B receptors, the modes also differed markedly in their mean closed durations and thus generated a broader range of open probabilities. We also found that regardless of gating mode, glutamate dissociation occurred similar to 4-fold more slowly (k_ = 15 s(-1)) compared to that observed in GluN1/GluN2A receptors. On the basis of these results, we suggest that slow glutamate dissociation and modal gating underlie the long heterogeneous activations of GluN1/GluN2B receptors.