Ubiquitination, also named as ubiquitylation, is a type of protein post-translational modification by adding ubiquitin to protein sequence. post translational modification ubiquitination is a universal regulatory protein that has been found in also all tissues. Ubiquitination modification is divided into two types: monoubiquitination and polyubiquitination, depending the number of ubiquitin molecule linked to proteins. The ubiquitination process contains a multiple enzymatic steps, with sequential action of ubiquitin-activating enzymes (E1), ubiquitin-conjugating enzymes (E2), and ubiquitin ligases (E3). The reaction catalyzed by each enzyme transfers a covalent bond with ubiquitin from one enzyme to the next and finally to a target protein.