MECHANISM OF PROTEIN TRANSLOCATION ACROSS MEMBRANES

这项研究旨在从分子水平上精确了解 某些种类的蛋白质被选择性地靶向并转移到 穿过哺乳动物细胞的内质网膜。我们将 鉴定蛋白质靶向的细胞成分， 易位机制是必不可少的，最终也是那些 是调节性的，以详细了解 以及单个分子所起的作用 在这个至关重要的过程中。具体而言，i）我们将 确定信号识别颗粒（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 这些相互作用受到调节。（二）确定个人 SRP中包含的三个GTIPs域中的每一个的贡献， 蛋白质靶向内质网期间的SRP受体 膜和蛋白质易位位点的组装。我们将 设计测定以鉴定影响结合的其他分子，和/或 通过单独的GTP酶域水解GTP。（三）我们将确定 新生链靶向所需的最小ER蛋白组， 新生链插入和新生链易位，并试图 破译这些蛋白质在这个过程中所起的作用。的 建议的研究显然是最基本的性质，毫无疑问， 这对于理解 在细胞和分子水平上的生理学和病理学。

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.