Assays for surface antigens in extracellular vesicles using proximity labeling strategy

Several studies have shown that extracellular vesicles (EVs) are biosynthesized in all cells and then transported to other cells in an endocrine or paracrine manner through the bloodstream. They are considered to be taken up via the EV receptor in the destination cell membrane, resulting in a subsequent intracellular signal transduction cascade induced by the contents inside EV particles (e.g., DNA, RNA, miRNA protein, etc.). Since EVs are synthesized and secreted by all cells, it is important to "classify" them for EV research. However, challenges such as the numerous types and large number of EVs in biological samples and the complexity of target antigens for classification necessitate the development of more effective experimental methods. This chapter discusses a novel strategy to identify specific EV surface markers for classifying EVs using the "proximity labeling" analysis, which labels proximal molecular groups typically used for protein-protein interaction analysis in recent years.