MECHANISM OF PROTEIN TRANSLOCATION ACROSS MEMBRANES

这项拟议中的研究旨在精确地从分子水平上了解 某些类别的蛋白质被选择性地靶向和转位 穿过哺乳动物细胞的内质网膜。我们会 鉴定蛋白质靶向的细胞成分并 转位机制是必不可少的，最终也是那些 都是可调节的，以获得对 靶向和移位以及单个分子所起的作用 在这一极其重要的过程中。具体来说，i)我们将 确定信号识别粒子(SRP)的分子细节- 信号序列相互作用和SRP-核糖体相互作用并询问如何 这些相互作用是受监管的。Ii)我们将确定个人 SRP和SRP中包含的三个GTP酶结构域中每个结构域的贡献 蛋白靶向内质网过程中的SRP受体 膜和蛋白质转位部位的组装。我们会 设计分析以确定影响结合和/或的其他分子 单个GTP酶结构域对GTP的水解酶活性。三)我们将确定 新生链靶向所需的最小一组ER蛋白， 新生的链插入和新生的链移位并尝试 破译这些蛋白质在这一过程中扮演的机械角色。这个 拟议的研究显然是最基本的性质，毫无疑问 这将对理解和理解 细胞和分子水平的生理学和病理学。

The proposed research aims at a precise molecular understanding of how certain classes of proteins are selectively targeted to and translocated across the endoplasmic reticulum membrane in mammalian cells. We will identify the cellular constituents of the protein targeting and translocation machinery that are essential, and ultimately also those that are modulatory, to gain a detailed understanding of the mechanism of targeting and translocation and the role which individual molecules play in this fundamentally important process. Specifically, i) we will determine the molecular details of signal recognition particle (SRP) - signal sequence interactions and SRP-ribosome interactions and ask how these interactions are regulated. ii) We will determine the individual contribution of each of the three GTPase domains contained in the SRP and the SRP receptor during protein targeting to the endoplasmic reticulum membrane and the assembly of the protein translocation site. We will design assays to identify other molecules that affect the binding and/or hydrolysis of GTP by individual GTPase domains. iii) We will determine the minimal set of ER proteins that is required for nascent chain targeting, nascent chain insertion and nascent chain translocation and try to decipher the mechanistic role that these protein play in the process. The proposed research is clearly of a most basic nature and there is no doubt that it will be of profound significance for an understanding of physiology and pathology at the cellular and molecular level.