analysis of protein ubiquitination

Ubiquitin is a small (8.6 kDa) regulatory protein and ubiquitination is an important post-translational modification, in which ubiquitins are attached to a substrate protein. This process contains three main steps: activation, conjugation, and ligation and requires three types of enzymes: ubiquitin-activating enzymes (E1s), ubiquitin-conjugating enzymes (E2s), and ubiquitin ligases (E3s).