Dopamine D2 receptors form higher order oligomers at physiological expression levels
Dopamine D2 receptors form higher order oligomers at physiological expression levels
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DOI：
10.1038/emboj.2008.153
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发表时间：
2008-09-03
期刊：
影响因子：
11.4
通讯作者：
Javitch, Jonathan A.
中科院分区：
文献类型：
--
作者：
Guo, Wen;Urizar, Eneko;Javitch, Jonathan A.
G蛋白偶联受体通常被认为是以二聚体的形式组织的;它们是否形成更高级的寡聚体是一个有争议的话题。我们结合了生物发光/荧光互补和能量转移，以证明至少有四个多巴胺D2受体位于在活的哺乳动物细胞中的分子接近，与它们在质膜上作为高阶低聚物的组织一致。这意味着存在多个受体接口。除了我们先前通过半胱氨酸（Cys）交联确定的第四跨膜段（TM 4）中的对称界面外，我们现在表明TM 1胞外端的一片残基形成了第二对称界面。交联的D2受体与半胱氨酸取代同时进入TM 1和TM 4导致更高级的物种，与我们的新的生物物理结果一致。值得注意的是，在受体表达的100倍范围内，两个界面的交联速率和程度没有改变。因此，在生理表达水平，受体在质膜中被组织成更高级的寡聚体结构。
G-protein-coupled receptors are generally thought to be organized as dimers; whether they form higher order oligomers is a topic of much controversy. We combined bioluminescence/fluorescence complementation and energy transfer to demonstrate that at least four dopamine D2 receptors are located in close molecular proximity in living mammalian cells, consistent with their organization as higher order oligomers at the plasma membrane. This implies the existence of multiple receptor interfaces. In addition to the symmetrical interface in the fourth transmembrane segment (TM4) we identified previously by cysteine (Cys) crosslinking, we now show that a patch of residues at the extracellular end of TM1 forms a second symmetrical interface. Crosslinking of D2 receptor with Cys substituted simultaneously into both TM1 and TM4 led to higher order species, consistent with our novel biophysical results. Remarkably, the rate and extent of crosslinking at both interfaces were unaltered over a 100-fold range of receptor expression. Thus, at physiological levels of expression, the receptor is organized in the plasma membrane into a higher order oligomeric structure.