IRF-2BP1 is a 584 amino acid nuclear protein belonging to the IRF-2BP family. IRF-2BP1 acts as a corepressor of IRF-2 that can inhibit both enhancer-activation and basal transcription in a manner that is not dependent upon histone deacetylation. IRF-2BP1 enhances the polyubiquitination of JDP2 (Jun-dimerization protein 2), a member of the c-Jun family of transcription factors. IRF-2BP1 contains a C-terminal RING-type zinc finger domain, which is necessary for interaction with BAP1 (BRCA1 associated protein 1). IRF-2BP1 is encoded by a gene located on human chromosome 19, which consists of over 63 million bases, houses approximately 1,400 genes and is recognized for having the greatest gene density of the human chromosomes.