Maturation of the Large Ribosomal Subunit in Yeast

描述（由申请人提供）：核糖体负责蛋白质合成，是所有细胞所必需的。它对遗传密码的忠实翻译和对其活动的适当调节是正常细胞生长和发育所必需的。核糖体组装是一个复杂的动态过程，必须存在确保核糖体正确组装的机制，以保持翻译的保真度。此外，核糖体的生物发生占快速分裂细胞能量消耗的很大一部分，必须与细胞的代谢需要协调。事实上，人类细胞增殖需要上调核糖体的生物发生。因此，了解调节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见解。对核糖体生物发生和翻译等基本细胞途径的描述也是智能开发新药所必需的，这些新药对其预期的细胞靶标具有特异性，而不会影响其他细胞途径。我们最近确定了酵母大核糖体亚基的核输出途径。我们发现它的输出依赖于输出适配器蛋白Nmd3p和输出受体Crm1，并且这种输出途径在人类细胞中是保守的。在本提案中，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。本提案将：1)解决输出适配器及其受体如何在大核糖体亚基上组装以介导输出。2)阐明在转运到细胞质后从亚基释放输出适配器所需的事件。3)确定Arx1 p和Reilp的功能，这两种功能相关蛋白在新生的大核糖体亚基出口和进入活性亚基细胞质库时作用于多肽出口通道。

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.