Ubiquitin-conjugating enzyme E2 L3 (UBE2L3), also called UBCH7, is a protein that in humans is encoded by the UBE2L3 gene. As an E2 enzyme, UBE2L3 participates in ubiquitination to target proteins for degradation. The role of UBE2L3 in the ubiquitination of the NF-κB precursor implicated it in various major autoimmune diseases, including rheumatoid arthritis (RA), celiac disease, Crohn's disease (CD), and systemic lupus erythematosus. The modification of proteins with ubiquitin is an important cellular mechanism for targeting abnormal or short-lived proteins for degradation. Ubiquitination involves at least three classes of enzymes: ubiquitin-activating enzymes (E1s), ubiquitin-conjugating enzymes (E2s) and ubiquitin-protein ligases (E3s). E2s play a key role in the whole ubiquitin (Ub) transfer pathway and are responsible for Ub cellular signaling. Unlike many E2s that transfer Ub with RINGs, UBE2L3 has E3-independent reactivity with lysine.[ This enzyme is demonstrated to participate in the ubiquitination of p53, c-Fos, and the NF-κB precursor p105 in vitro. UBE2L3 is primarily known for its role in the cell cycle. Specifically, UBE2L3 manages cell cycle regulatory protein levels via the ubiquitin proteolytic pathway (UPP) during the G1/S transition and during the actual S phase.