Maturation of the Large Ribosomal Subunit in Yeast

描述(申请人提供)：核糖体负责蛋白质合成，在所有细胞中都是必不可少的。它对遗传密码的忠实翻译和对其活动的适当调节对于正常的细胞生长和发育是必要的。核糖体组装是一个复杂而动态的过程，必须存在机制来确保核糖体的正确组装，以保持翻译的保真度。此外，核糖体生物合成占快速分裂细胞能量消耗的很大一部分，必须与细胞的新陈代谢需求相协调。事实上，人类的细胞增殖需要上调核糖体的生物生成。因此，了解调控核糖体生物发生的机制将为开发控制疾病状态下细胞增殖的新工具提供洞察力。描述核糖体、生物发生和翻译等基本细胞途径对于智能开发针对其预期细胞靶点的新药也是必要的，而不会影响其他细胞途径。我们最近发现了酵母中核糖体大亚基的核输出途径。我们发现它的输出依赖于输出适配蛋白Nmd3p和输出受体CRM1，并且这一输出途径在人类细胞中是保守的。在这项提案中，我们将使用我们在NmdSp研究中开发的试剂来扩展这些初步发现。这一建议将：1)解决出口适配器及其受体如何组装在大的核糖体亚基上以介导出口。2)阐明在运送到细胞质后将输出适配器从亚单位释放所需的事件。3)确定Arx1p和Reilp这两个功能相关的蛋白质的功能，这两个蛋白质在新生的大核糖体亚基出口和进入活性亚基的细胞质库时，作用于多肽出口隧道。

DESCRIPTION (provided by applicant): The ribosome is responsible for protein synthesis and is essential in all cells. Its faithful translation of the genetic code and the proper regulation of its activity are necessary for normal cell growth and development. Ribosome assembly is a complex and dynamic process and mechanisms must exist that ensure the correct assembly of ribosomes in order to maintain the fidelity of translation. In addition, ribosome biogenesis accounts for a large portion of the energy expenditure of a rapidly dividing cell and must be coordinated with the metabolic needs of a cell. Indeed, cell proliferation in humans requires upregulation of ribosome biogenesis. Thus, understanding the mechanisms regulating ribosome biogenesis will provide insight for the development of new tools for controlling cell proliferation in disease states. The delineation of fundamental cellular pathways such as ribosome biogenesis and translation is also necessary for the intelligent development of new drugs that are specific to their intended cellular targets without impinging on other cellular pathways. We recently identified the nuclear export pathway for the large ribosomal subunit in yeast. We showed that its export depends on the export adapter protein Nmd3p and the export receptor Crm1 and that this export pathway is conserved in human cells. In this proposal, we will expand on these initial findings using reagents that we have developed in our studies of NmdSp. This proposal will: 1) Address how the export adapter and its receptor assemble on the large ribosomal subunit to mediate export. 2) Elucidate the events required to release the export adapter from the subunit after delivery to the cytoplasm. 3) Determine the function of Arx1 p and Reilp, two functionally related proteins that act at the polypeptide exit tunnel on the nascent large ribosomal subunit during export and as it enters the cytoplasmic pool of active subunits.