Stabilizing effects of G protein on the active conformation of adenosine A1 receptor differ depending on G protein type
Stabilizing effects of G protein on the active conformation of adenosine A1 receptor differ depending on G protein type
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G 蛋白对腺苷 A1 受体活性构象的稳定作用因 G 蛋白类型而异
DOI：
10.1016/j.ejphar.2016.06.025
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发表时间：
2016
影响因子：
5
通讯作者：
Kubo Y
中科院分区：
文献类型：
--
作者：
Tateyama M;Kubo Y
G蛋白偶联受体(GPCRs)在与配体结合时可触发多种细胞和生理反应。配体结合诱导GPCRs的构象变化，从而使G蛋白与受体相互作用。G蛋白的相互作用也影响GPCRs的活性构象。在本研究中，我们观察了GαI1、Gα0和嵌合GαQ5对腺苷A1受体活性构象的影响，因为每种Gα与腺苷A1受体的相互作用不同。当激动剂导致腺苷A1受体的两个胞内区融合的荧光蛋白之间的Förster共振能量转移(FRET)效率降低时，腺苷A1受体的构象变化被检测到。当FP标记的腺苷A1受体单独表达时，激动剂诱导的FRET下降的幅度很小，而当与Gαi1Gβ1Gγ22(Gi1)或Gαq5Gβ1Gγ22(Gq5)共同表达时，FRET下降的幅度显著增加，而与GαοGβ1Gγ22(GO)共同表达则不明显。Gq5对激动剂诱导的FRET降低的促进作用明显大于Gi1。此外，在Gq5存在的情况下，去除激动剂后的FRET恢复明显慢于Gi1。这些结果表明，腺苷A1受体激动剂结合的活性构象在没有G蛋白结合的情况下是不稳定的，并且G蛋白的稳定作用因G蛋白的类型而异。
G protein coupled receptors (GPCRs) trigger various cellular and physiological responses upon the ligand binding. The ligand binding induces conformational change in GPCRs which allows G protein to interact with the receptor. The interaction of G protein also affects the active conformation of GPCRs. In this study, we have investigated the effects of Gαi1, Gαoand chimeric Gαqi5on the active conformation of the adenosine A1receptor, as each Gαshowed difference in the interaction with adenosine A1receptor. The conformational changes in the adenosine A1receptor were detected as the agonist-induced decreases in efficiency of Förster resonance energy transfer (FRET) between fluorescent proteins (FPs) fused at the two intracellular domains of the adenosine A1receptor. Amplitudes of the agonist-induced FRET decreases were subtle when the FP-tagged adenosine A1receptor was expressed alone, whereas they were significantly enhanced when co-expressed with Gαi1Gβ1Gγ22 (Gi1) or Gαqi5Gβ1Gγ22 (Gqi5) but not with GαοGβ1Gγ22 (Go). The enhancement of the agonist-induced FRET decrease in the presence of Gqi5 was significantly larger than that of Gi1. Furthermore, the FRET recovery upon the agonist removal in the presence of Gqi5 was significantly slower than that of Gi1. From these results it was revealed that the agonist-bound active conformation of adenosine A1receptor is unstable without the binding of G protein and that the stabilizing effects of G protein differ depending on the types of G protein.