Modified RING finger, HC subclass (C3HC3D-type), found in tripartite motif-containing protein 23 (TRIM23) and similar proteins
TRIM23, also known as ADP-ribosylation factor domain-containing protein 1, GTP-binding protein ARD-1, or RING finger protein 46 (RNF46), is an E3 ubiquitin-protein ligase belonging to the C-IX 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 modified C3HC3D-type RING-HC finger, Bbox1 and Bbox2, and a coiled coil region, as well as C-terminal ADP ribosylation factor (ARF) domains. TRIM23 is involved in nuclear factor (NF)-kappaB activation. It mediates atypical lysine 27 (K27)-linked polyubiquitin conjugation to NF-kappaB essential modulator NEMO, also known as IKKgamma, which plays an important role in the NF-kappaB pathway, and this conjugation is essential for TLR3- and RIG-I/MDA5-mediated antiviral innate and inflammatory responses. It also regulates adipocyte differentiation via stabilization of the adipogenic activator peroxisome proliferator-activated receptor gamma (PPARgamma) through atypical ubiquitin conjugation to PPARgamma. Moreover, TRIM23 interacts with and polyubiquitinates yellow fever virus (YFV) NS5 to promote its binding to STAT2 and trigger type I interferon (IFN-I) signaling inhibition.