Figure 2.

Target protein degradation through proteolysis-targeting chimeras (PROTAC). A bifunctional small molecule PROTAC compound is consist of ligand (circle in orange color) that binds the protein of interest (POI, light blue) and ligand (circle in green) for an E3 ubiquitin ligase (E3, rectangle in dark blue). Both ligands are connected by a linker. The binding of PROTAC compound to both POI and E3 ubiquitin ligase results in ternary complex formation, leading to addition of ubiquitin (circle in red) to POI that is degraded by proteasome inside the cells.