β2 adrenergic receptor activation -: Modulation of the proline kink in transmembrane 6 by a rotamer toggle switch
β2 adrenergic receptor activation -: Modulation of the proline kink in transmembrane 6 by a rotamer toggle switch
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DOI：
10.1074/jbc.m206801200
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发表时间：
2002-10-25
影响因子：
4.8
通讯作者：
Javitch, JA
中科院分区：
文献类型：
--
作者：
Lei, S;Liapakis, G;Javitch, JA
在许多视紫红质样 G 蛋白偶联受体中，与 TM6 中芳香族残基簇结合的激动剂可以通过改变 TM6 Pro-kink 的构型以及随后 TM6 的细胞质末端远离 TM3 的运动来促进受体激活。我们假设高度保守的Cys(6.47)位于保守的Pro(6.50)附近，通过其不同旋转异构体构型中的特定相互作用来调节芳香族簇和TM6 Pro扭结的构型。在β2肾上腺素能受体中，Cys(6.47)突变为Thr，其在α-螺旋中具有与Cys和Ser不同的旋转异构体分布，产生组成型活性受体，而Ser突变体与野生型受体相似。使用构象记忆的偏向蒙特卡罗技术表明，Cys/Ser/Thr(6.47)、Trp(6.48)和Phe(6.52)之间的旋转异构体变化高度相关，代表可能调节TM6 Pro-kink的旋转异构体“切换开关”。野生型和组成型活性背景中Cys(6.47)和工程化Cys(6.52)的可及性的差异调节为该旋转异构体开关与受体激活的关联提供了实验支持。
In many rhodopsin-like G-protein-coupled receptors, agonist binding to a cluster of aromatic residues in TM6 may promote receptor activation by altering the configuration of the TM6 Pro-kink and by the subsequent movement of the cytoplasmic end of TM6 away from TM3. We hypothesized that the highly conserved Cys(6.47), in the vicinity of the conserved Pro(6.50), modulates the configuration of the aromatic cluster and the TM6 Pro-kink through specific interactions in its different rotamer configurations. In the beta2 adrenergic receptor, mutation Of Cys(6.47) to Thr, which in an alpha-helix has a different rotamer distribution from Cys and Ser, produced a constitutively active receptor, whereas the Ser mutant was similar to wild-type receptor. Use of the biased Monte Carlo technique of Conformational Memories showed that the rotamer changes among Cys/Ser/Thr(6.47), Trp(6.48), and Phe(6.52) are highly correlated, representing a rotamer "toggle switch" that may modulate the TM6 Pro-kink. Differential modulation of the accessibility Of Cys(6.47) and an engineered Cys(6.52) in wild type and a constitutively active background provides experimental support for the association of this rotamer switch with receptor activation.