E3 ubiquitin-protein ligase that mediates ubiquitination and subsequent proteasomal degradation of target proteins, such as DDX58/RIG-I, MAVS/IPS1, IFIH1/MDA5, JAK1 and p53/TP53. Acts as a negative regulator of type I interferon production by mediating ubiquitination of DDX58/RIG-I at 'Lys-181', leading to DDX58/RIG-I degradation. Mediates ubiquitination and subsequent degradation of p53/TP53. Mediates ubiquitination and subsequent degradation of JAK1. Acts as a positive regulator of T-cell activation. 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 UBE2D1. Interacts with VCP/p97; leading to recruit RNF125 to DDX58/RIG-I and promote ubiquitination of DDX58/RIG-I. Shows a reticular staining pattern within the cell and is probably expressed at other intracellular membranes in addition to the Golgi membrane. Not detected at the plasma membrane. The C2HC RNF-type zinc finger and the linker region stabilize the RING-type zinc finger, leading to promote binding of the RING-type zinc finger to the ubiquitin-conjugating enzyme E2 (donor ubiquitin). Autoubiquitinated, leading to its subsequent proteasomal degradation.