Among all the mechanisms of protein degradation in the cell, one can separately highlight the ubiquitin-proteasomal system, the principle of which is based on the selective tagging of proteins by a ligase complex using ubiquitinylation.

Such a tag facilitates recognition by the proteasome, a protein machine capable of degrading proteins associated with a chain of several ubiquitins.

Thanks to UPS, it is possible to recognize changes in the structure of proteins that were caused by mutation, malfunction, or successful completion of a functional cycle, and decompose such “undesirable” proteins.

The PROTAC (PROTeolysis TArgeting Chimera) concept is based on the principle of creating an induced proximity of the ligase complex and POI in such a way that protein-protein interactions arise between them, mediating acts of ubiquitinylation and subsequent proteasomal degradation.