Regulator of Notch signaling, a signaling pathway involved in cell-cell communications that regulates a broad spectrum of cell-fate determinations. Probably acts both as a positive and negative regulator of Notch, depending on the developmental and cell context. Functions as a ubiquitin ligase protein in vitro, suggesting that it may regulate the Notch pathway via some ubiquitin ligase activity. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Homodimer. May form a heterodimer with other members of the Deltex family. Interacts with NOTCH1. Strongly expressed in testis and brain. Weakly expressed in kidney. In the CNS, it is expressed in the developing neural tube starting from 10.5 dpc in the spinal cord and around 11.5 dpc in the telencephalon. Expressed ubiquitously throughout the spinal cord and telencephalon during neurogenesis. Expressed throughout the developing retina at 15.5 dpc. Not expressed in the somite or presomite during somitogenesis. Expressed slightly later that Dtx2. Belongs to the Deltex family.