UBE2E3: ProductsUbiquitin-conjugating Enzyme E2E 3 (UBE2E3), also known as Ubiquitin-conjugating Enzyme H9 (UbcH9), is a member of the Ubiquitin-conjugating (E2) enzyme family. UBE2E3 has a predicted molecular weight of 23 kDa. The human protein shares 100% amino acid sequence identity with the mouse and rat orthologs. UBE2E3 has an E2 catalytic core domain with an active site cysteine residue that is required for the formation of a thioester bond with Ubiquitin. This enzyme appears to be localized in the nucleus of interphase cells and cell-wide in mitotic cells. UBE2E3 may be regulated at the post-transcriptional level by miR-143. The auto-ubiquitination of the ARA54, RNF8, and bacterially-encoded NleG Ubiquitin ligases (E3s) is mediated by UBE2E3. UBE2E3 also functions with NEDD4L to regulate ENaC activity. Physiologically, UBE2E3 is required for the proliferation of retinal pigment epithelial cells via the negative regulation of p27/Kip1 levels. UBE2E3 may also be required for HIV-1 replication.