Transcriptional regulator that plays a central role in Notch signaling, a signaling pathway involved in cell-cell communication that regulates a broad spectrum of cell-fate determinations. Acts as a transcriptional repressor when it is not associated with Notch proteins. When associated with some NICD product of Notch proteins (Notch intracellular domain), it acts as a transcriptional activator that activates transcription of Notch target genes. Probably represses or activates transcription via the recruitment of chromatin remodeling complexes containing histone deacetylase or histone acetylase proteins, respectively. Specifically binds to the immunoglobulin kappa-type J segment recombination signal sequence. Binds specifically to methylated DNA (PubMed:21991380). Binds to the oxygen responsive element of COX4I2 and activates its transcription under hypoxia conditions (4% oxygen) (PubMed:23303788). Negatively regulates the phagocyte oxidative burst in response to bacterial infection by repressing transcription of NADPH oxidase subunits (By similarity). Interacts with activated NOTCH1, NOTCH2 or NOTCH3. Interacts with MINT/SHARP. This interaction may mediate the recruitment of large corepressor complexes containing proteins such as HDAC1, HDAC2, NCOR2, SAP30, FHL1/KYOT2 and CIR1. Interacts with EP300, MAML1 and PTF1A. Interacts with Epstein-Barr virus EBNA2, EBNA3, EBNA4 and EBNA6. Interacts with RITA1/C12orf52, leading to nuclear export, prevent the interaction between RBPJ and NICD product and subsequent down-regulation of the Notch signaling pathway. Interacts with SNW1. Interacts with CHCHD2 and CXXC5 (PubMed:23303788). Interacts with BEND6 (via BEN domain). Interacts with NKAPL (By similarity). Interacts with ZMIZ1. Interacts with RBM15 (By similarity). Mainly nuclear, upon interaction with RITA/C12orf52, translocates to the cytoplasm, down-regulating the Notch signaling pathway. The disease is caused by variants affecting the gene represented in this entry. Belongs to the Su(H) family. Despite some similarity with the 'phage' integrase family, it has no recombinase activity. Truncated N-terminus.