E3 ubiquitin-protein ligase that promotes the ubiquitination of different substrates (PubMed:27880896). In turn, participates in different biological processes including interferon production or autophagy (PubMed:26456228, PubMed:27880896). Plays a role in the activation of RNA virus-induced interferon-beta production by promoting the ubiquitination of TRAF3 and TRAF6 (PubMed:26456228). Also plays a role in the early recruitment of autophagy adapters to bacteria (PubMed:27880896). Mediates 'Lys-29' and 'Lys-33'-linked ubiquitination of SQSTM1 leading to xenophagic targeting of bacteria and inhibition of their replication (PubMed:27880896). 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.