E3 ubiquitin-protein ligase. Seems to utilize UBE2E1. In vitro, generates polyubiquitin chains via non-canonical lysine residues suggesting that it is not involved in tagging substrates for proteasomal degradation. 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. Expressed in alveolar epithelial type II cells. Induced in lung during endotoxemia. By LPS and inflammatory cytokines in alveolar epithelial type II cells. Extended N-terminus.