Ube2E1 is an E2 enzyme, which is part of the E1, E2, and E3 cascade responsible for ubiquitination of protein substrates. Ube2E1 was found to locate in the nucleus. It, along with Ube2D1, is known to complex with the E3 ligase Ro52 to ubiquitinate interferon regulatory transcription factors IRF3 and IRF8. Ube2E1 can also complex with a Ub ligase called RING105 to ubiquitinate a tumor suppressor known as tumor – suppressing subchromosomal transferable fragment cDNA (TSSC5).