MECHANISM OF MACROMOLECULAR EXPORT FROM THE NUCLEUS

描述（改编自申请人的摘要）：RNA的输出和 蛋白质从细胞核进入细胞质是细胞的基本功能 是真核生物基因表达调控的关键步骤。的 控制这些传输事件的机制仍然知之甚少 但非洲爪蟾卵母细胞的动力学竞争研究表明， 不同的RNA类别，包括mRNA、snRNA、tRNA和rRNA，使用不同的 出口通道。由于大多数（如果不是全部的话）RNA与蛋白质相关， 在细胞核中，RNA输出事件由 蛋白质，有人认为，RNA输出事件是 由含有适当核输出信号（NES）的蛋白质介导。 这得到了小的可转移信号的识别的支持， 导致其从细胞核快速而活跃地输出的蛋白质。的 这项研究的长期目标是表征不同的RNA， 以及酵母S.为了了解酿酒厂 在分子水平上的核输出机制。更具体地说， 提出了三个具体目标：（1）P.I.将描述 核输出因子1（Xpo 1p/Crm1p）及其在mRNA表达中的作用 导出.将采用各种生物化学和遗传学方法， 确定与Xpo1p相互作用的因素。GTTRAN在以下方面的作用 调节Xpo 1p与其他细胞因子的相互作用将是 检查了在mRNA输出中介导Xpo 10作用的衔接子 将被定性。(2)NES介导的核蛋白输出 机器将被分解。将探索遗传方法， 确定NES蛋白质出口机制的其他组成部分。这 输出途径将被用作模型系统，以了解分子 大分子如何通过核孔运输的细节 复合体进入细胞质。(3)最后私家侦探将决定是否 在酵母中存在不同的RNA输出途径。原位标记固定和 活细胞将用于表征不同RNA的输出 在几个突变的背景类。如果不同的路径 确定，调解和调节这些出口事件的因素将是 鉴定

DESCRIPTION (adapted from the applicant's abstract): Export of RNA and protein from the nucleus into the cytoplasm is a fundamental cellular process and a key step in the control of eukaryotic gene expression. The mechanisms governing these transport events are still poorly understood but kinetic competition studies in Xenopus oocytes have indicated that different RNA classes, including mRNA, snRNA, tRNA and rRNA use distinct export pathways. Since most, if not all RNAs, are associated with proteins in the nucleus it was suggested that RNA export events are mediated by proteins in the nucleus it was suggested that RNA export events are mediated by proteins containing appropriate nuclear export signals (NESs). This is supported by the identification of small transferable signals in proteins that cause their rapid and active export from the nucleus. The long-term goal of the proposed research is to characterize different RNA and protein export pathways in the yeast S. cerevisiae and to understand the nuclear export mechanisms at a molecular level. More specifically, three specific aims are proposed: (1) The P.I. will characterize the nuclear export factor export in 1 (Xpo1p/Crm1p) and its role in mRNA export. A variety of biochemical and genetic approaches will be used to identify factors which interact with Xpo1p. The role of the GTPase Ran in regulating the interaction of Xpo1p with other cellular factors will be examined and the adapter(s) that mediate(s) Xpo10,s role in mRNA export will be characterized. (2) The NES-mediated nuclear protein export machinery will be dissected. Genetic approaches will be explored to identify additional components of the NES-protein export machinery. This export pathway will be used as a model system to understand the molecular details of how macromolecules are transported through the nuclear pore complex into the cytoplasm. (3) Finally, the P.I. will determine whether distinct RNA export pathways exist in yeast. In situ labeling in fixed and live cells will be used to characterize the export of the different RNA classes in several mutant backgrounds. If distinct pathways are identified, factors that mediate and regulate these export events will be identified.