MATURATION OF THE LARGE RIBOSOMAL SUBUNIT IN YEAST

描述（来自应用程序）：本提案旨在了解 酵母中核糖体大亚基的生物发生及其在 翻译.核糖体对所有细胞的生存能力都是必不可少的。在 活跃生长的细胞，核糖体生物合成占了很大一部分， 细胞的能量消耗和因此核糖体的生物合成必须 与细胞的代谢需求相协调。细胞快速增殖 需要核糖体生物合成的上调。从而控制核糖体 生物发生对正常发育很重要。 我们鉴定了Nmd 3 p，它是酵母中的一个保守的和必需的蛋白质， 在大亚基（60 S）的生物发生的后期步骤所需的。我们有 最近表明，Nmd 3 p与60 S亚基形成稳定的复合物， 该复合物含有新生和成熟亚基。因此，Nmd 3 p是 连接核糖体生物合成和翻译的蛋白质。在本提案中，我们 将使用遗传和生物化学技术来确定Nmd 3 p在 亚基的生物发生及其在翻译中的作用。这项工作将涉及 新生和成熟游离60 S核糖体亚基的纯化， 提供了这些复合物的第一个物理特性。 除了分析Nmd 3 p之外，我们还将测试两个模型的功能 由Ski 2 p、Ski 3 p和Ski 8 p组成的蛋白质复合物。SKI中的突变 基因导致poly（A）- mRNA的翻译升高， mRNA的3 '-降解。解释这些结果的两个模型是， 正常60 S功能需要复合物，或者该复合物以 3 '-mRNA降解途径。将进行实验以区分 这两个模型之间。

DESCRIPTION (from the application): This proposal is directed at understanding biogenesis of the large ribosomal subunit in yeast and its recruitment into translation. The ribosome is essential for the viability of all cells. In actively growing cells, ribosome biogenesis accounts for a large part of the energy expenditure of the cell and consequently ribosome biogenesis must be coordinated with the metabolic needs of a cell. Rapid cellular proliferation requires upregulation of ribosome biogenesis. Thus control of ribosome biogenesis is important for normal development. We identified Nmd3p, a conserved and essential protein in yeast, that is required for a late step in biogenesis of the large (60S) subunit. We have recently shown that Nmd3p forms a stable complex with 60S subunits and that this complex contains both nascent and mature subunits. Thus, Nmd3p is a protein that couples ribosome biogenesis and translation. In this proposal we will use genetic and biochemical techniques to determine the role of Nmd3p in subunit biogenesis as well as its role in translation. This work will involve the purification of nascent and mature free 60S ribosomal subunits and will provide the first physical characterization of these complexes. In addition to the analysis of Nmd3p we will test two models for the function of the protein complex composed of Ski2p, Ski3p and Ski8p. Mutations in the SKI genes result in elevated translation of poly(A)- mRNA and reduced 3'-degradation of mRNA. Two models accounting for these results are that this complex is required for normal 60S function or that this complex acts in a 3'-mRNA degradation pathway. Experiments will be carried out to distinguish between these two models.