Huq Enamul, Al-Sady Bassem, Quail Peter H
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Plant J. 2003 Sep;35(5):660-4. doi: 10.1046/j.1365-313x.2003.01836.x.
The phytochrome (phy) family of sensory photoreceptors (phyA to phyE in Arabidopsis) enables plants to optimize their growth and development under natural light environments. Subcellular localization studies have shown that the photoreceptor molecule is induced to translocate from cytosol to nucleus by light, but direct evidence of the functional relevance of this translocation has been lacking. Here, using a glucocorticoid receptor-based fusion protein system, we demonstrate that both photoactivation and nuclear translocation combined are necessary and sufficient for the biological function of phyB. Conversely, neither artificial nuclear translocation of non-photoactivated phyB nor artificial retention of photoactivated phyB in the cytosol provides detectable biological activity. Together these data indicate that signal transfer from photoactivated phyB to its primary signaling partner(s) is localized in the nucleus, and conversely suggest the absence of a cytosolic pathway from photoactivated phyB to light-responsive genes.
植物感光光受体的光敏色素（phy）家族（拟南芥中的phyA至phyE）使植物能够在自然光环境下优化其生长和发育。亚细胞定位研究表明，光受体分子受光诱导从细胞质转移至细胞核，但这种转移功能相关性的直接证据一直缺乏。在此，我们使用基于糖皮质激素受体的融合蛋白系统证明，光激活和核转移相结合对于phyB的生物学功能是必要且充分的。相反，未光激活的phyB的人工核转移或光激活的phyB在细胞质中的人工滞留均未提供可检测到的生物学活性。这些数据共同表明，从光激活的phyB到其主要信号伴侣的信号传递定位于细胞核，相反，这也表明不存在从光激活的phyB到光响应基因的细胞质途径。
