A post-translational change known as ubiquitination occurs when the ubiquitin protein is joined to a substrate protein.
The ubiquitin-activating enzyme (E1), Ubiquitin-conjugating enzyme (E2), and Ubiquitin-protein ligase are the three enzymes involved in the three-step process (E3).
The process of ubiquitination, in which several copies of the tiny protein ubiquitin are attached, targets cyclins, Cdk inhibitor proteins, and other cell-cycle regulators for breakdown.
Giant protease complexes known as proteasomes identify and digest ubiquitinated proteins.
A group of enzymes collectively referred to as E1, E2, and E3 enzymes carry out a sequence of events known as ubiquitination, including ubiquitin activation, conjugation, and ubiquitin-protein ligation.