UbcH5a/UBE2D1: ProductsUbiquitin-conjugating Enzyme H5a (UbcH5a), also known as Ubiquitin-conjugating Enzyme E2D 1 (UBE2D1), is a ubiquitously expressed protein that is related to Stimulator of Iron Transport (SFT). Human UbcH5a/UBE2D1 has a predicted molecular weight of 17 kDa and shares 89% and 88% amino acid (aa) sequence identity with the related family members UbcH5b and UbcH5c, respectively. Human UbcH5a/UBE2D1 shares 100% aa sequence identity with the mouse and rat orthologs. UbcH5a/UBE2D1 has a conserved E2 catalytic core domain that contains an active site cysteine residue, and it interacts with a variety of HECT and RING finger Ubiquitin ligases (E3) to mediate the ubiquitination of specific target proteins. UbcH5a/UBE2D1 interacts with the E3, E6-AP, to conjugate Ubiquitin to the tumor suppressor, p53. Additional protein targets of UbcH5a/UBE2D1 include c-Fos, RIP1, and HIF-1. Pathologically, UbcH5a/UBE2D1 is implicated in protein degradation during cancer and immune responses.