高尔基体在真核细胞蛋白分泌、分选和运输中起中心作用。GRASPs蛋白在高尔基体扁平囊堆叠中起着关键作用。目前尚不清楚GRASPs是如何介导扁平囊堆叠形成高尔基体的。我们初步研究发现了一种新颖的相互作用可以改变GRASP55蛋白结构，可能与GRASPs蛋白在高尔基体囊膜堆叠中调节变化相关。本项目申请拟在此基础上通过突变潜在的作用位点进一步研究多肽与GRASP55 PDZ结构域的相互作用，此相互作用位点与之前报道的GM130在GRASP65 PDZ结构域上的结合位点相似。我们也计划解析GRASP65与GM130衍生多肽复合物以及GRASP55与新发现的golgin45的复合物结构。比较这些复合物结构及其分子排列堆积方式、分析复合物结合底物前后的结构变化及其相互作用对分子排列的影响，结合免疫荧光及电镜等生物化学及细胞生物学技术深入揭示GRASPs蛋白在高尔基体囊膜堆叠中作用的结构基础和分子机理。

The Golgi apparatus is comprised of stacks of flattened cisterneas and maintains its characteristic structure in spite of high dynamic vesicular traffic. It plays the key role in the protein secreting, sorting and trafficking in eukaryotic cells，but the molecular mechanisms responsible for its assembly and organization remain poorly understood. Our preliminary result indicates a new interaction between the PDZ domain of GRASP55 and a special peptide. This interaction can alter the structure of GRASP55 and form a network like structure. It may relate to the transition of Golgi in the stacking process. This project proposes to study the interaction between GRASP55 and this special peptide by mutagenesis based on this new discovery. In addition, we plan to solve the complex structures of the GRASP55 PDZ domain with golgin 45 and GRASP65 PDZ domain with the peptides derived from GM130 which was reported binding to the GRASP domain at the position similar to the interaction site in our new structure. The aim of this study is to understand the structural basis and molecular mechanism of Golgi cisternae stacking mediated by GRASPs by analyzing the conformation change and molecular rearrangement in all 3 complex structures and the related change of Golgi complex showed by immunofluorescence and EM techniques.