Light-dependent activation of G proteins by two isoforms of chicken melanopsins.
Light-dependent activation of G proteins by two isoforms of chicken melanopsins.
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鸡黑视蛋白的两种亚型对 G 蛋白的光依赖性激活。
DOI：
10.1039/c5pp00153f
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Yoshitaka Fukada
中科院分区：
文献类型：
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作者：
Masaki Torii;Daisuke Kojima;Akiyuki Nishimura Hiroshi Itoh;Yoshitaka Fukada
在鸡松果体中，光刺激触发由两种不同亚型Gt和G11介导的信号通路。这些G蛋白可能被激活的任何三个主要的松果体视蛋白，视松，OPN 4 -1和OPN 4 -2，但生化证据的耦合已经失踪，除了视松和GT之间的功能耦合。在这里，我们调查的相对表达水平和功能之间的差异松果体视蛋白。在鸡松果体中，视松素的mRNA表达量显著高于其它几种，其中OPN 4 - 2的mRNA表达量高于OPN 4 -1。在G蛋白激活试验中，Gt被视胞素以光依赖的方式强烈激活，与先前的研究一致，而被OPN 4 -2弱激活。出乎意料的是，照射的0 PN 4 -2更有效地激活培养物中HEK 293 T细胞内源性表达的G蛋白。另一方面，Gq，G11的最接近的类似物，仅被OPN 4 -1激活，尽管在这些条件下活性相对较弱。这些结果表明，OPN 4 -1和OPN 4 -2分别与Gq和Gt偶联。两种黑视素，OPN 4 -1和OPN 4 -2，似乎通过进化获得了相互不同的功能。
In the chicken pineal gland, light stimuli trigger signaling pathways mediated by two different subtypes, Gtand G11. These G proteins may be activated by any of the three major pineal opsins, pinopsin, OPN4-1 and OPN4-2, but biochemical evidence for the coupling has been missing except for functional coupling between pinopsin and Gt. Here we investigated the relative expression levels and the functional difference among the three pineal opsins. In the chicken pineal gland, the pinopsin mRNA level was significantly more abundant than the others, of which theOPN4-2mRNA level was higher than that ofOPN4-1. In G protein activation assays, Gtwas strongly activated by pinopsin in a light-dependent manner, being consistent with previous studies, and weakly activated by OPN4-2. Unexpectedly, illuminated OPN4-2 more efficiently activated G protein(s) that was endogenously expressed in HEK293T cells in culture. On the other hand, Gq, the closest analogue of G11, was activated only by OPN4-1 although the activity was relatively weak under these conditions. These results suggest that OPN4-1 and OPN4-2 couple with Gqand Gt, respectively. Two melanopsins, OPN4-1 and OPN4-2, appear to have acquired mutually different functions through the evolution.