This thesis aims to comprehensively explore ligand-based approaches of the Renin-Angiotensin System, with a particular focus on ACE2 and AT2R, in order to advance our understanding of their roles in health and disease. The study's diverse methodologies encompass covalent binding strategies, radioligand binding assays and fluorescent microscopy techniques. The ultimate goal is to contribute valuable insights into the intricate RAS, paving the way for novel therapeutic strategies and expanding ligand-based approaches in GPCR research.