RING finger, HC subclass, found in tripartite motif-containing protein 56 (TRIM56) and similar proteins
TRIM56, also known as RING finger protein 109 (RNF109), is a virus-inducible E3 ubiquitin ligase that restricts pestivirus infection. It positively regulates the Toll-like receptor 3 (TLR3) antiviral signaling pathway, and possesses antiviral activity against bovine viral diarrhea virus (BVDV), a ruminant pestivirus classified within the family Flaviviridae shared by tick-borne encephalitis virus (TBEV). It also possesses antiviral activity against two classical flaviviruses, yellow fever virus (YFV) and dengue virus (DENV), as well as a human coronavirus, HCoV-OC43, which is responsible for a significant share of common cold cases. It may do not act on positive-strand RNA viruses indiscriminately. Moreover, TRIM56 is an interferon-inducible E3 ubiquitin ligase that modulates STING to confer double-stranded DNA-mediated innate immune responses. TRIM56 belongs to the C-V subclass of TRIM (tripartite motif) family of proteins that are defined by an N-terminal RBCC (RING, Bbox, and coiled coil) domains, including three consecutive zinc-binding domains, a C3HC4-type RING-HC finger, Bbox1 and Bbox2, and a coiled coil region, as well as an uncharacterized region positioned C-terminal to the RBCC domain.