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 vivo, mediating ubiquitination and promoting degradation of MEKK1, 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. May form a homo- or heterodimer with other members of the Deltex family. Probably interacts with Notch1. Specifically expressed in regions undergoing neuronal differentiation. Mainly colocalizes with Notch1. In the tailbud stage, it is expressed in the olfactory bulbs, pineal complex and along the neural tube according to an antero-posterior gradient showing a gap at the midbrain-hindbrain boundary. At tadpole stage, it is expressed in the differentiating retina, in the neuronal fibers of the outer and inner plexiform layers, while its expression in the pineal complex becomes restricted to the photosensitive frontal organ. The WWE domains are thought to mediate some protein-protein interaction, and are frequently found in ubiquitin ligases. Belongs to the Deltex family.