NCIt definition : Ubiquitin protein ligase enzymes catalyze the formation of a covalent peptide bond
between the carboxy-terminal glycine of ubiquitin proteins and lysine alpha-amino
group of other proteins. This typically marks proteins for either nonlysosomal proteasomal
degradation or targeted transport. Ubiquitination requires sequential action of an
activating enzyme, a conjugating enzyme, and a ligase.;