E3 ubiquitin-protein ligase that mediates ubiquitination and subsequent proteasomal degradation of NKD2. Stimulates transcription mediated by NF-kappa-B. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Interacts with UBE2D2, and may also interact with UBE2E1 and UBE2E3. Interacts with RELA and NKD2 (By similarity). The RING-type zinc finger domain interacts with an ubiquitin-conjugating enzyme (E2) and facilitates ubiquitination. Ubiquitinated.