Skip to main content
. 2015 Dec 18;7(6):6521–6537. doi: 10.18632/oncotarget.6658

Figure 2. illustration of the ubiquitin proteasome system (UPS).

Figure 2

The ubiquitin (Ub) is first activated by E1 in an ATP-dependent manner. The activated ubiquitin is then transferred to E2. E3 forms a complex with the target protein (or substrate) and recruits the E2-ubiquitin complex. The activated ubiquitin is then transferred from E2 to the target protein. This ubiquitination process can be reversed by deubiquitinating enzymes (DUBs). Finally, the ubiquitinated target gets recognized and degraded by the 26S proteasome. Several compounds targeting E1, E2, E3, DUBs and the proteasome have been studied, from which some of them are currently approved for the treatment of MM, while others are still under (pre)-clinical investigation.