The ubiquitin (Ub) pathway involves three sequential enzymatic steps that facilitate the conjugation of Ub and Ub-like molecules to specific protein substrates. The first step requires ATP-dependent activation of the Ub C-terminus and assembly of multi-Ub chains by a Ub-activating enzyme known as the E1 component. The Ub chain is then conjugated to the Ub-conjugating enzyme (E2) to generate an intermediate Ub-E2 complex. The Ub-ligase (E3) then catalyzes the transfer of Ub from E2 to the appropriate protein substrate. UBE2U (ubiquitin-conjugating enzyme E2U) is a 321 amino acid E2 ubiquitin conjugating enzyme that catalyzes the covalent attachment of ubiquitin to other proteins. Existing as two alternatively spliced isoforms, UBE2U is encoded by a gene located on human chromosome 1, which spans 260 million base pairs, contains over 3,000 genes and comprises nearly 8% of the human genome.