Abstract: The present invention relates to a method of identifying an intracellular secretory protein or tissue-specific secretory protein, by using a proximity labeling system. When the method according to the present invention is used, it is possible to clearly identify an intracellular secretory protein and to dynamically track the spatiotemporal dynamics of a secretory protein secreted from a specific tissue in a living subject such that it can be effectively utilized for the research on endocrine signals between tissues, and particularly, since it can be applied in situ, the scope of application can be further expanded. Therefore, the present invention can be applied to various disease models or tissues to discover new biomarkers and therapeutic target proteins associated with diseases.