variant of RING finger, HC subclass, found in interferon regulatory factor 2 (IRF2)-binding protein 2 (IRF-2BP2)
IRF-2BP2, also known as IRF-2-binding protein 2 or DIF-1, is a nuclear protein that binds to the C-terminal repression domain of IRF-2 and acts as an IRF-2-dependent transcriptional corepressor, both enhancer-activated and basal transcription. IRF-2BP2 also specifically interacts with the C-terminal domain of the nuclear factor of activated T cells NFAT1 transcription factor, and negatively regulates the NFAT1-dependent transactivation of NFAT-responsive promoters. Moreover, IRF2BP2 suppresses the transactivation activity of p53 on both Bax and p21 promoters. It also shows anti-apoptotic activity through the modulation of a death domain in NRIF3. In addition, IRF2BP2 functions as a cofactor of VGLL4 and plays a critical role controlling gene expression in skeletal, cardiac, and smooth muscle cells. It is a muscle-enriched transcription factor required to activate vascular endothelial growth factor-A (VEGF-A) expression in muscle. IRF-2BP2 contains an N-terminal C4-type zinc finger and a C-terminal C3HC4-type RING-HC finger with a partially new pattern. The zinc finger is responsible for the homo- and hetero-dimerization between different members of the IRF-2BP2 family. The RING-HC finger interacts with IRF2 and also with nuclear receptor interacting factor 3 (NRIF3).