Different mechanisms that promote protein monoubiquitination

Protein monoubiquitination is a post-translational modification that consists of the conjugation of a single ubiquitin molecule to a target protein residue. Monoubiquitination regulates protein activity and localization and is involved in DNA repair, histone regulation, and receptor endocytosis. Although the mechanisms by which monoubiquitination regulates protein function are still not well understood, there are some insights into the mechanisms that promote this modification. In this work, we discuss some of the principles of the processes that produce monoubiquitination in vivo; i.e., how ubiquitin conjugating enzymes, ubiquitin ligases or other co-factors can produce direct substrates monoubiquitination, and how ubiquitin specific proteases can indirectly convert polyubiquitinated to monoubiquitinated proteins.