POLY A NUCLEASE AND TRANSLATION INITIATION IN YEAST

描述（改编自申请人的摘要）：信使RNA（mRNA） 真核细胞中的翻译起始需要以下协同作用： 几种不同的途径。 例如，核糖体亚基必须保持 在没有mRNA的情况下解离，mRNA必须被包装成一种形式， 核糖体亚基可以识别的基因。 的第一步 翻译起始是40S的5'到3'方向扫描 在mRNA上的核糖体亚基，直到它结合到起始密码子。 的 第二步是60S核糖体亚基的连接，以形成 单核糖体 本提案的目的是了解该机制， 酵母中60S核糖体亚基连接步骤的调节，等等 一般理解真核细胞中的mRNA识别。 过去的工作 表明60S亚基连接步骤需要poly（A）尾 mRNA。 最近，多聚（A）核糖核酸酶（PAN）被认为是一种 调解员这一要求。 这里描述的实验概述了如何 PAN在翻译中的作用将在体外使用PAN依赖的 翻译摘录。 他们将探讨PAN与 核糖体，并确定PAN或其他蛋白质中的突变是否与 他们将定义PAN磷酸化的重要性 及其在翻译途径中的相关激酶。 最后 pan1突变体表型和基因外抑制子的表征 和PAN的合成致命突变，将被追求，以获得更多的 深入了解PAN在体内的功能。 这项工作的结果可能提供 更详细地了解真核生物中的基本反应， 细胞 所得结果可为今后的工作探索铺平道路 在细胞转化或感染过程中，这种途径发生改变。

DESCRIPTION (Adapted from Applicant's Abstract): Messenger RNA (mRNA) translation initiation in eucaryotic cells requires the concerted action of several different pathways. For instance, ribosomal subunits must be kept dissociated in the absence of mRNA, and mRNA must be packaged into a form that will be recognized by the ribosomal subunits. The first step in translation initiation is the 5' to 3' directional scanning of the 40S ribosomal subunit on the mRNA until it binds to the initiator codon. The second step is the joining of the 60S ribosomal subunit to form the monoribosome. The goal of this proposal is to understand the mechanism and regulation of the 60S ribosomal subunit joining step in yeast, and more generally to understand mRNA recognition in eucaryotic cells. Past work suggests that the 60S subunit joining step requires the poly(A) tail on mRNA. Recently the poly(A) ribonuclease (PAN) has been implicated as a mediator of this requirement. The experiments described here outline how PAN's role in translation will be studied in vitro using PAN-dependent translation extracts. They will explore PAN's association with the ribosome and determine if mutations in PAN or in other proteins interacting with PAN effect it. They will define the importance of PAN phosphorylation and of its associated kinase in the translation pathways. Finally, the characterization of pan1 mutant phenotypes, and of extragenic suppressors and synthetic lethal mutations with PAN, will be pursued to gain more insight into PAN's function in vivo. The results of this work may provide a more detailed understanding of a fundamental reaction in eucaryotic cells. The results obtained may pave the way for future work exploring alterations of this pathways during cellular transformation or infection.