Sorting of seed storage proteins in developing seeds: Formation of transport vesicles and interdependence of different sorting pathways

植物种子贮藏蛋白直接或间接作为主食对人类营养是必不可少的。贮藏蛋白质可占种子干重的30%以上。在双子叶植物，如豆类和油菜的成熟过程中，种子贮藏蛋白沉积在发育中的胚胎中的特殊液泡中，即蛋白质储存液泡。蛋白质通过不同的囊泡运输途径到达这些液泡，包括笼蛋白包裹的囊泡(CCV)，以及迄今为止唯一的致密囊泡(DV)介导的途径。这些途径似乎是相互依存的。本研究旨在利用免疫电子显微镜在分子和超微结构水平上研究这两条途径进入拟南芥胚胎PSV的相互依赖关系。我们将在转基因拟南芥野生型植物和缺失对这两条运输途径重要的受体和胞浆蛋白的缺失突变体的种子中，将分子运输标记的分类与确定的空泡分类决定因素进行比较。我们将在分子水平上研究顺式高尔基体上DV的形成。我们将使用生化、蛋白质组学和反向遗传方法来识别和表征与货物蛋白质聚集有关的蛋白质。

Plant seed storage proteins are essential for human nutrition, either directly or indirectly as staple food. Storage proteins can make up to more than 30% of the dry weight of the seed. During maturation of dicotyledonous plants, like legumes and rape, seed storage proteins are deposited in specialized vacuoles, the protein storage vacuoles PSV), in the developing embryo. Proteins reach these vacuoles via different vesicular transport routes, the Clathrin Coated Vesicle (CCV), and the, hitherto unique, Dense Vesicle (DV) mediated pathways. These pathways appear to be interdependent. This proposal aims at investigating the interdependence of these two pathways into the PSV of Arabidopsis embryos on a molecular and ultrastructural level, employing immuno electron-microscopy. We will compare the sorting of molecular transport markers with defined vacuolar sorting determinants in seeds of transgenic Arabidopsis wild type plants and deletion mutants devoid of receptors and cytosolic proteins important for these two transport routes. We will investigate the formation of the DV at the cis-Golgi apparatus on a molecular level. We will employ biochemical, proteomic, and reverse genetic approaches to identify and characterize proteins which are involved in the aggregation of cargo proteins.