Seven transmembrane receptor core signaling complexes are assembled prior to plasma membrane trafficking
Seven transmembrane receptor core signaling complexes are assembled prior to plasma membrane trafficking
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DOI：
10.1074/jbc.m605012200
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发表时间：
2006-11-10
影响因子：
4.8
通讯作者：
Hebert, Terence E.
中科院分区：
文献类型：
--
作者：
Dupre, Denis J.;Robitaille, Melanie;Hebert, Terence E.
关于β 2肾上腺素能受体在长时间激动剂刺激后的运输和内化，我们已经知道很多。然而，关于β 2-肾上腺素能受体向质膜的向外运输或运输在受体信号复合物组装中可能发挥的作用知之甚少，这对随后信号事件的靶向、特异性和快速性很重要。在这里，通过使用生物发光共振能量转移，双分子荧光互补和共聚焦显微镜的组合，我们评估了核心受体-G蛋白异源三聚体复合物形成的步骤。通过使用显性负性Rab和Sar GTPase构建体，我们证明受体二聚体和受体-G β γ复合物最初在内质网中结合，而G α亚基在内质网-高尔基体转运期间添加到复合物中。我们还观察到G蛋白异源三聚体在单独表达或与受体化学计量共表达时采用不同的运输路线。此外，这些复合物的特定组分的故意错误定位导致其他成员从其正常的亚细胞定位转移，证实了这些早期相互作用在靶向和形成特定信号复合物中的作用。
Much is known about beta(2)-adrenergic receptor trafficking and internalization following prolonged agonist stimulation. However, less is known about outward trafficking of the beta(2)-adrenergic receptor to the plasma membrane or the role that trafficking might play in the assembly of receptor signaling complexes, important for targeting, specificity, and rapidity of subsequent signaling events. Here, by using a combination of bioluminescence resonance energy transfer, bimolecular fluorescence complementation, and confocal microscopy, we evaluated the steps in the formation of the core receptor-G protein heterotrimer complex. By using dominant negative Rab and Sar GTPase constructs, we demonstrate that receptor dimers and receptor-G beta gamma complexes initially associate in the endoplasmic reticulum, whereas G alpha subunits are added to the complex during endoplasmic reticulum-Golgi transit. We also observed that G protein heterotrimers adopt different trafficking itineraries when expressed alone or with stoichiometric co-expression with receptor. Furthermore, deliberate mistargeting of specific components of these complexes leads to diversion of other members from their normal subcellular localization, confirming the role of these early interactions in targeting and formation of specific signaling complexes.