E3 ubiquitin-protein ligase that catalyzes 'Lys-11'- or 'Lys-33'-linked polyubiquitin chains, with some preference for 'Lys-33' linkages (PubMed:25752577). E3 ubiquitin-protein ligases accept ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfers the ubiquitin to targeted substrates (PubMed:23479728, PubMed:31578312). Ubiquitinates SEPTIN4, DIABLO/SMAC and HTRA2 in vitro (PubMed:23479728). Modulates pulmonary inflammation by targeting SOCS2 for ubiquitination and subsequent degradation by the proteasome (PubMed:31578312). 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 SOCS2 (PubMed:31578312). Interacts (via HECT domain) with HTRA2, DIABLO/SMAC and SEPTIN4; in the cytoplasm following induction of apoptosis (PubMed:23479728). Autoubiquitinated in vitro in the presence of E2 enzyme UBE2D1/UBCH5A. Extended N-terminus.