UBE2E3 is a ubiquitin-conjugating enzyme (E2) that accepts ubiquitin from E1 enzymes and catalyzes its covalent attachment to target proteins 1. The enzyme catalyzes multiple polyubiquitination linkages, including Lys-11, Lys-48, and Lys-63 modifications, and contains a critical cysteine-145 residue essential for ubiquitin conjugation 1. UBE2E3 localizes to the nucleus and cytosol, regulating diverse cellular processes. It modulates TDP-43 ubiquitination and solubility, with implications for frontotemporal lobar degeneration and amyotrophic lateral sclerosis pathogenesis 2. UBE2E3 controls the antioxidant transcription factor NRF2 distribution and activity by regulating its ubiquitination and nuclear localization 3. The enzyme is essential for retinal pigment epithelial cell proliferation and is downregulated during RPE differentiation 4. Loss of UBE2E3 induces cellular senescence through p53/p21-dependent mechanisms, linked to dysregulated autophagy and mitochondrial dynamics 5. UBE2E3 expression is regulated by miRNAs—miR-143-3p promotes ovarian granulosa cell senescence via UBE2E3 suppression 6, while miR-379-5p downregulation in breast cancer impacts cell viability through UBE2E3 targeting 7. These findings establish UBE2E3 as a critical regulator of ubiquitin-dependent proteolysis with roles in cellular senescence, neurodegenerative diseases, and cancer.