Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, USA.
Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA.
Cell Rep. 2021 Oct 26;37(4):109891. doi: 10.1016/j.celrep.2021.109891.
The kainate receptors (KARs) are members of the ionotropic glutamate receptor family and assemble into tetramers from a pool of five subunit types (GluK1-5). Each subunit confers distinct functional properties to a receptor, but the compositional and stoichiometric diversity of KAR tetramers is not well understood. To address this, we first solve the structure of the GluK1 homomer, which enables a systematic assessment of structural compatibility among KAR subunits. Next, we analyze single-cell RNA sequencing data, which reveal extreme diversity in the combinations of two or more KAR subunits co-expressed within the same cell. We then investigate the composition of individual receptor complexes using single-molecule fluorescence techniques and find that di-heteromers assembled from GluK1, GluK2, or GluK3 can form with all possible stoichiometries, while GluK1/K5, GluK2/K5, and GluK3/K5 can form 3:1 or 2:2 complexes. Finally, using three-color single-molecule imaging, we discover that KARs can form tri- and tetra-heteromers.
红藻氨酸受体（KARs）是离子型谷氨酸受体家族的成员，由五个亚基类型（GluK1-5）组成四聚体。每个亚基赋予受体独特的功能特性，但 KAR 四聚体的组成和化学计量多样性尚不清楚。为了解决这个问题，我们首先解决了 GluK1 同源体的结构，这使得能够对 KAR 亚基之间的结构兼容性进行系统评估。接下来，我们分析了单细胞 RNA 测序数据，这些数据揭示了同一细胞内共表达的两个或更多 KAR 亚基的组合存在极端多样性。然后，我们使用单分子荧光技术研究了单个受体复合物的组成，发现由 GluK1、GluK2 或 GluK3 组装的二异源四聚体可以形成所有可能的化学计量比，而 GluK1/K5、GluK2/K5 和 GluK3/K5 可以形成 3:1 或 2:2 复合物。最后，使用三色单分子成像，我们发现 KAR 可以形成三聚体和四聚体。
