RING finger, HC subclass, found in tripartite motif-containing protein 68 (TRIM68) and similar proteins
TRIM68, also known as RING finger protein 137 (RNF137) or SSA protein SS-56 (SS-56), is an E3 ubiquitin-protein ligase that negatively regulates Toll-like receptor (TLR)- and RIG-I-like receptor (RLR)-driven type I interferon production by degrading TRK fused gene (TFG), a novel driver of IFN-beta downstream of anti-viral detection systems. It also functions as a cofactor for androgen receptor-mediated transcription through regulating ligand-dependent transcription of androgen receptor in prostate cancer cells. Moreover, TRIM68 is a cellular target of autoantibody responses in Sjogren"s syndrome (SS), as well as systemic lupus erythematosus (SLE). It is also an auto-antigen for T cells in SS and SLE. TRIM68 belongs the C-IV subclass of TRIM (tripartite motif) family of proteins that are defined by their N-terminal RBCC (RING, Bbox, and coiled coil) domains, including three consecutive zinc-binding domains, a C3HC4-type RING-HC finger, a B-box, and two coiled coil domains, as well as a B30.2/SPRY (SplA and ryanodine receptor) domain positioned C-terminal to the RBCC domain.