Nissan Tracy A, Bassler Jochen, Petfalski Elisabeth, Tollervey David, Hurt Ed
Biochemie-Zentrum Heidelberg, Universität Heidelberg, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
EMBO J. 2002 Oct 15;21(20):5539-47. doi: 10.1093/emboj/cdf547.
60S ribosomes undergo initial assembly in the nucleolus before export to the cytoplasm and recent analyses have identified several nucleolar pre-60S particles. To unravel the steps in the pathway of ribosome formation, we have purified the pre-60S ribosomes associated with proteins predicted to act at different stages as the pre-ribosomes transit from the nucleolus through the nucleoplasm and are then exported to the cytoplasm for final maturation. About 50 non-ribosomal proteins are associated with the early nucleolar pre-60S ribosomes. During subsequent maturation and transport to the nucleoplasm, many of these factors are removed, while others remain attached and additional factors transiently associate. When the 60S precursor particles are close to exit from the nucleus they associate with at least two export factors, Nmd3 and Mtr2. As the 60S pre-ribosome reaches the cytoplasm, almost all of the factors are dissociated. These data provide an initial biochemical map of 60S ribosomal subunit formation on its path from the nucleolus to the cytoplasm.
60S核糖体在输出到细胞质之前先在核仁中进行初始组装，最近的分析已经鉴定出几种核仁前60S颗粒。为了阐明核糖体形成途径中的步骤，我们纯化了与预测在不同阶段发挥作用的蛋白质相关的前60S核糖体，这些前核糖体从核仁穿过核质，然后输出到细胞质进行最终成熟。约50种非核糖体蛋白与早期核仁前60S核糖体相关。在随后的成熟和向核质运输过程中，许多这些因子被去除，而其他因子则保留附着状态，并且有额外的因子短暂结合。当60S前体颗粒接近从细胞核输出时，它们与至少两种输出因子Nmd3和Mtr2结合。当60S前核糖体到达细胞质时，几乎所有因子都解离。这些数据提供了60S核糖体亚基从核仁到细胞质的形成路径的初始生化图谱。
