Atypical E3 ubiquitin ligase that can catalyze ubiquitination of both proteins and lipids, and which is involved in various processes, such as lipid metabolism, angiogenesis and cell-autonomous immunity (PubMed:21799892, PubMed:26126547, PubMed:26278786, PubMed:26766444, PubMed:30705059, PubMed:32139119, PubMed:34012115). Acts as a key immune sensor by catalyzing ubiquitination of the lipid A moiety of bacterial lipopolysaccharide (LPS) via its RZ-type zinc-finger: restricts the proliferation of cytosolic bacteria, such as Salmonella, by generating the bacterial ubiquitin coat through the ubiquitination of LPS (PubMed:34012115). Also acts indirectly by mediating the recruitment of the LUBAC complex, which conjugates linear polyubiquitin chains (PubMed:34012115). Ubiquitination of LPS triggers cell-autonomous immunity, such as antibacterial autophagy, leading to degradation of the microbial invader (PubMed:34012115). Involved in lipid metabolism by regulating fat storage and lipid droplet formation; act by inhibiting the lipolytic process (PubMed:30705059). Also regulates lipotoxicity by inhibiting desaturation of fatty acids (PubMed:30846318). Also acts as an E3 ubiquitin-protein ligase via its RING-type zinc finger: mediates ‘Lys-63’-linked ubiquitination of target proteins (PubMed:32139119, PubMed:33842849). Involved in the non-canonical Wnt signaling pathway in vascular development: acts by mediating ubiquitination and degradation of FLNA and NFATC2 downstream of RSPO3, leading to inhibit the non-canonical Wnt signaling pathway and promoting vessel regression (PubMed:26766444). Also has ATPase activity; ATPase activity is required for ubiquitination of LPS (PubMed:34012115).
