植物为人类和牲畜生存提供所需蛋白质，也能合成生物活性分子，其合成蛋白质的能力强，但积累目的蛋白的能力有限，其中可溶性蛋白的积累需经过选择性的分选和转运，这个过程的核心是蛋白分选受体识别特定的分选信号将可溶性蛋白分选到细胞区室中。利用植物生产蛋白受两方面限制：第一，不同植物分选受体与配体互作的机制不清晰；第二，蛋白质储存的细胞内区室空间有限。本课题组开发了一种以纳体-抗原决定簇互作为基础的创新技术，可用于体内区室特异性的受体-配体互作分析。通过研究VSR和RMR两大受体蛋白家族，确定配体结合/释放的区室和受体的内源配体及其转运途径；其次，本课题组将通过驱动膜泡形成的跨膜结构域(TMD)的表达来诱导细胞内区室形成。基于这些TMD和VSR/RMR的腔内配体结合域合成纳体-抗原决定簇互作驱动的自组装的嵌合分选受体，进而把诱导新区室形成和蛋白质分选功能结合起来以获得目的蛋白的最大积累。

Plant-produced proteins are an indispensable source of food for mankind and livestock and are also utilized for biomedical applications. Plants have an almost unlimited capacity to synthesize proteins but their capacity for storing these proteins is limited. Almost all of these proteins are soluble proteins and their accumulation requires selective sorting and transport processes. At the heart of these processes operate protein sorting receptors that sort the soluble proteins based on specific sorting signals with high efficiency into a stable intracellular compartment.The full exploitation of plants for the production of proteins is currently limited by two major facts: 1st limited knowledge of the molecular mechanisms of receptor-ligand interaction of the different plant sorting receptors and 2nd, the availability of suitable intracellular compartments for protein storage.We have most recently developed innovative molecular tools and experimental strategies that are based on the utilization of nanobody-epitope interaction to achieve non-invasive, compartment-specific analysis of receptor-ligand interactions in vivo. Our recently published data on vacuolar sorting receptor 4 (VSR4) have resulted in a fundamental revision of the view on receptor-mediated sorting of vacuolar proteins. Here we propose to extend our successful analysis of protein sorting receptors to the members of the VSR protein family VSR5, VSR6, and VSR7, whose function could not have been established to date using the conventional approaches. We also propose to analyze all six members of the RMR receptor protein family (RMR1-6), all of which have not been characterized in vivo yet. In this comprehensive analysis, we will identify the compartments in which ligand binding/release occurs, we will identify endogenous ligands and characterize the transport routes of the respective receptors.In a second focus, we propose the exploration of the possibility to induce the biogenesis of novel intracellular compartments by the expression of transmembrane domains (TMDs) that drive membrane vesiculation. We propose to generate chimeric nanobody-epitope interaction-driven self-assembling sorting receptors based on these TMDs and the luminal ligand binding domains of the VSR/RMR proteins. This combines the induction of the compartment with the protein sorting function.We see this as a highly innovative key strategy to revolutionize protein production in plants.