E3 ubiquitin ligase that plays a crucial role in the activation of the IKBKE-dependent branch of the type I interferon signaling pathway (PubMed:24882218). In concert with the ubiquitin-conjugating E2 enzyme UBE2K, synthesizes unanchored 'Lys-48'-linked polyubiquitin chains that promote the oligomerization and autophosphorylation of IKBKE leading to stimulation of an antiviral response (PubMed:24882218). Ubiquitinates also MYC and inhibits its transcription activation activity, maintaining the pluripotency of embryonic stem cells (PubMed:22328504). 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. Homotrimer. Forms heteromultimers (via B30.2/SPRY domain) with TRIM5 (By similarity). Interacts with MYC (PubMed:22328504). Interacts (via SPRY domain) with IKBKE (By similarity). Interacts with VAMP8; this interaction contributes to the activation of the type I interferon antiviral response (By similarity). The B-box zinc finger and the linker region between the coiled coil and B30.2/SPRY domains contribute to higher order self-association. Belongs to the TRIM/RBCC family.