细胞内蛋白质的定向转移是蛋白质质量数量控制体系的一个重要环节，信号识别颗粒(Signal recognition particle, SRP) 及蛋白分子伴侣 SecB介导的蛋白识别转运则是其中普遍存在的机制之一，尤其是蛋白的靶向输送（protein targeting）机制的研究对揭示细胞的分化、代谢和病变具有重大的理论意义。本课题利用蛋白质组学技术，鉴定依赖于SRP和SecB转运途径的底物蛋白。BONCAT技术用来标记、纯化新合成蛋白。细胞组分分离用于分离细胞质中前体蛋白和亚细胞器中蛋白。SILAC技术用于定量分析依赖于SRP和SecB转运途径的蛋白。本工作将会为蛋白定位的分子机制提供基础，揭示很多由于突变而中断蛋白定位、转运，而引起的遗传和免疫病变的机制，也为工业微生物改变蛋白转运途径，提高目标产物产量，降低生产成本提供理论依据。

Proper localization and quantification of proteins is essential to establish and maintain order and organization in all cells. The signal recognition particle (SRP) and chaperone (SecB) constitute the major cellular machinery that delivers nascent membrane and secretory proteins to the membrane. In this study, an unbiased proteomic approach will be used to identify the protein substrates delivered by the SRP and SecB pathways. Bioorthogonal noncanonical amino acid tagging (BONCAT) will be used to selectively label newly synthesized proteins and facilitate their purification. Cell fractionation will be used to separate untargeted precursor proteins from membrane and secretory proteins. SILAC will be used to identify proteins whose cellular localization are depended on SRP or SecB. This work will provide a basis for elucidation of the molecular principles that determine the localization of a protein in a cell, for unravelling the mechanism of many hereditary and autoimmoune diseases that result from mutations disrupting protein targeting and trafficking, and for providing the mechanism of industrial application by altering the protein targeting pathway.