fig1
Figure 1. The ubiquitin-proteasome proteolytic pathway. The process of protein degradation via the ubiquitin-proteasome pathway is mediated by an organized milieu of activating (E1), conjugating (E2) and ligating (E3) enzymes to regulate the ligation of ubiquitin to the protein substrate. The substrate attached with multiple ubiquitin molecules are targeted to the 26S proteasome complex for degradation. Ubiquitin molecules can be removed by the action of deubiquitinating enzymes.