Acts as a ligand for Notch (N) receptor. Essential for proper differentiation of ectoderm. Dl is required for the correct separation of neural and epidermal cell lineages. Fringe (fng) acts in the Golgi to determine the type of O-linked fucose on the EGF modules in N, altering the ability of N to bind with Delta (Dl). O-fut1 also has a role in modulating the interaction. Interacts with N via the EGF repeats and the N EGF repeats. Detected in all areas with neurogenic abilities, for example the neurogenic ectoderm and the primordia of the sense organs. Later expression is restricted to those cells that have adopted a neural fate. Expressed both maternally and zygotically. Expression is highest early in embryonic development (stage 5) and reduces to a low level during larval stages. Ubiquitinated by Mib, leading to its endocytosis and subsequent degradation. Separation of neuroblasts from the ectoderm into the inner part of embryo is one of the first steps of CNS development in insects, this process is under control of the neurogenic genes. Notch and Serrate may interact at the protein level, it is conceivable that the Serrate and Delta proteins may compete for binding with the Notch protein. Truncated N-terminus.