Promotes loss of intracellular domain (ICD) of Notch1 in embryos. By down-regulating ICD levels, could function as a negative feedback regulator of Notch signaling that attenuates ICD-mediated transcription (By similarity). Involved in angiogenesis. May be involved in somitogenesis (By similarity). Forms a ternary complex with the intracellular domain (ICD) of notch1 and rbpj/suh. Belongs to the NRARP family.