Inhibits primary neurogenesis. May be required to divert neurons along a specific differentiation pathway. Plays a role in the formation of somite boundaries during segmentation of the paraxial mesoderm. Can bind and activate Notch-1 or another Notch receptor. Predominantly expressed in the neuroectoderm and paraxial mesoderm during embryogenesis. The DSL domain is required for binding to the Notch receptor. Ubiquitinated by MIB (MIB1 or MIB2), leading to its endocytosis and subsequent degradation. A truncating mutation in Dll3 is the cause of the pudgy (pu) phenotype. Pudgy mice exhibit patterning defects at the earliest stages of somitogenesis. Adult pudgy mice present severe vertebral and rib deformities.