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.