Instituto de Bioquímica Vegetal y Fotosíntesis-Consejo Superior de Investigaciones Científicas, CSIC, Avda. Américo Vespucio, Sevilla, Spain.
Plant Signal Behav. 2012 Feb;7(2):273-5. doi: 10.4161/psb.18767. Epub 2012 Feb 1.
The highly conserved target of rapamycin (TOR) Ser/Thr kinase promotes protein synthesis under favorable growth conditions in all eukaryotes. Downregulation of TOR signaling in the model unicellular green alga Chlamydomonas reinhardtii has recently revealed a link between control of protein synthesis, endoplasmic reticulum (ER) stress and the reversible modification of the BiP chaperone by phosphorylation. Inhibition of protein synthesis by rapamycin or cycloheximide resulted in the phosphorylation of BiP on threonine residues while ER stress induced by tunicamycin or heat shock caused the fast dephosphorylation of the protein. Regulation of BiP function by phosphorylation/dephosphorylation events was proposed in early studies in mammalian cells although no connection to TOR signaling has been established so far. Here I will discuss about the coordinated regulation of BiP modification by TOR and ER stress signals in Chlamydomonas.
雷帕霉素（TOR）丝氨酸/苏氨酸激酶这一高度保守的靶标在所有真核生物中促进有利生长条件下的蛋白质合成。在模式单细胞绿藻衣藻中下调 TOR 信号通路，最近揭示了蛋白质合成、内质网（ER）应激和 BiP 伴侣蛋白通过磷酸化实现的可逆修饰之间的联系。雷帕霉素或环己酰亚胺抑制蛋白质合成导致 BiP 上苏氨酸残基磷酸化，而衣霉素或热休克引起的 ER 应激导致蛋白快速去磷酸化。尽管目前尚未建立与 TOR 信号通路的联系，但在哺乳动物细胞的早期研究中就提出了通过磷酸化/去磷酸化事件调节 BiP 功能的假说。在这里，我将讨论 TOR 和 ER 应激信号在衣藻中对 BiP 修饰的协调调节。
