Kim-Ha J, Kerr K, Macdonald P M
Department of Biological Sciences, Stanford University, California 94305-5020, USA.
Cell. 1995 May 5;81(3):403-12. doi: 10.1016/0092-8674(95)90393-3.
Oskar (osk) protein directs the deployment of nanos (nos), the posterior body-patterning morphogen in Drosophila. To avoid inappropriate activation of nos, osk activity must appear only at the posterior pole of the oocyte, where the osk mRNA becomes localized during oogenesis. Here, we show that translation of osk mRNA is, and must be, repressed prior to its localization; absence of repression allows osk protein to accumulate throughout the oocyte, specifying posterior body patterning throughout the embryo. Translational repression is mediated by an ovarian protein, bruno, that binds specifically to bruno response elements (BREs), present in multiple copies in the osk mRNA 3'UTR. Addition of BREs to a heterologous mRNA renders it sensitive to translational repression in the ovary.
奥斯卡（Oskar，简称osk）蛋白指导果蝇中nanos（nos）蛋白的分布，nanos是一种决定果蝇胚胎后部身体模式的形态发生素。为避免nos蛋白的不适当激活，osk蛋白的活性必须仅出现在卵母细胞的后极，在卵子发生过程中osk信使核糖核酸（mRNA）会定位于此处。在这里，我们表明，osk mRNA的翻译在其定位之前受到抑制，而且必须受到抑制；缺乏这种抑制会使osk蛋白在整个卵母细胞中积累，从而决定整个胚胎的后部身体模式。翻译抑制由一种卵巢蛋白布鲁诺（bruno）介导，该蛋白特异性结合osk mRNA 3'非翻译区（UTR）中多个拷贝存在的布鲁诺反应元件（BREs）。将BREs添加到异源mRNA中会使其在卵巢中对翻译抑制敏感。
