植物细胞内质网产生多种特殊囊泡，参与多种细胞成分的转运，是植物独特生长发育和环境响应的进化产物。十字花科植物特有的内质网小体富含芥子油苷酶，在植物防御反应中发挥重要作用。申请人通过研究拟南芥内质网小体形成关键因子NAI2的互作蛋白NAIPs，发现了一类新型内质网NAIP囊泡，是十字花科内质网小体的进化祖先，在植物界广泛存在，但它们的生物学功能尚不清楚。申请人还发现了两个NAIP互作蛋白ION1和ION2，也是这类新型内质网囊泡的组成蛋白。本项目拟在此基础上，通过囊泡分离和蛋白组学，鉴定这类植物特有的新型内质网囊泡的组成成分包括装载的蛋白，分析它们参与的生物学过程及生物学功能；继续研究NAIP互作蛋白ION1和ION2，进一步解析NAIP囊泡的形成机制。阐明这类植物新型内质网囊泡的生物学功能和形成机制对拓展植物细胞生物学研究领域，为植物改良提供新途径具有重要意义。

Plant cells produce many types of endoplasmic reticulum (ER)-derived vesicles involved in the trafficking of various types of cellular components and as such they are cellular structures evolved for the unique features of plants growth, development and environmental responses. The ER bodies presently only in Brassicaceae family accumulate myrosinases that hydrolyzes glucosinolates and play an important role in plant defense responses. During the study of a group of Arabidopsis proteins, NAIPs, which interact with the NAI2 protein critical for the formation of the ER body, the applicant of this project discovered a novel type of ER-derived vesicles—— NAIP vesicles, which are the evolutionary ancestors of ER bodies and are present in all plants. The biological functions of this new type of ER-derived structures are currently unknown. In addition, the applicant has recently identified two NAIP-interacting proteins, ION1 and ION2, and have demonstrated that they are associated with ER-derived vesicles. Based on these findings, this proposed project will seek to isolate the novel type of the ER-derived vesicles, determine their protein composition using proteomic approaches, including their cargo proteins and analyze the biological processes in which they are involved. The project will also continue functional analysis of NAIP-interacting ION1 and ION2 proteins in order to further dissect the mechanisms of biogenesis of the NAIP vesicles. Elucidation of the biological functions and biogenesis mechanisms of the NAIP vesicles will be highly significant for expanding the research field of plant cell biology and discovery of new avenues of plant improvement.