Essential signaling protein which has a major role in many developmental processes (PubMed:3935325). Functions as a receptor for membrane-bound ligands Delta and Serrate to regulate cell-fate determination (PubMed:10935637, PubMed:15620650, PubMed:12909620, PubMed:18243100). Upon ligand activation, and releasing from the cell membrane, the Notch intracellular domain (NICD) forms a transcriptional activator complex with Su(H) (Suppressor of hairless) and activates genes of the E(spl) complex (PubMed:7671825). Regulates oogenesis, the differentiation of the ectoderm and the development of the central and peripheral nervous system, eye, wing disk, muscles and segmental appendages such as antennae and legs, through lateral inhibition or induction (PubMed:11719214, PubMed:12369105, PubMed:3935325). Regulates neuroblast self-renewal, identity and proliferation through the regulation of bHLH-O proteins; in larval brains, involved in the maintenance of type II neuroblast self-renewal and identity by suppressing erm expression together with pnt; might also regulate dpn expression through the activation of the transcriptional regulator Su(H) (PubMed:27151950, PubMed:28899667, PubMed:20152183, PubMed:18342578, PubMed:23056424, PubMed:21262215). Homomer. Interacts with Su(H) when activated. Interacts with Dx via its ANK repeats. Interacts with Dl via the EGF repeats and the Dl EGF repeats. Interacts with Nedd4 and Su(dx). Interacts with O-fut1; the interaction glycosylates N and transports N to early endosomes. Interacts with Akap200; the interaction stabilizes N/Notch protein levels by preventing Cbl-mediated ubiquitination and subsequent lysosomal degradation of N/Notch (PubMed:29309414). Transported to early endosomes by O-fut1 (PubMed:17329366). Upon activation and S3 cleavage, it is released from the cell membrane and enters into the nucleus in conjunction with Su(H). Crystal structure of the ANK repeat domain shows that there are 7 repeats and the stabilizing C-terminal repeat enhances the protein stability by extending the ankyrin domain. Upon binding its ligands such as Delta or Serrate, it is cleaved (S2 cleavage) in its extracellular domain, close to the transmembrane domain. S2 cleavage is probably mediated by Kuz. It is then cleaved (S3 cleavage) downstream of its transmembrane domain, releasing it from the cell membrane. S3 cleavage requires Psn. O-glycosylated (PubMed:27268051). Three forms of O-glycosylation (O-fucosylation, O-glucosylation and O-GlcNAcylation) are detected (PubMed:27268051). O-fucosylated by O-fut1 and fng in the EGF repeat domain inhibits both Serrate/Ser- and Delta/Dl-binding (PubMed:12909620, PubMed:10935637). O-glucosylation by rumi in the endoplasmic reticulum is necessary for correct folding and signaling (PubMed:18243100). Ubiquitinated by Nedd4; which promotes ligand-independent endocytosis and proteasomal degradation. May also be ubiquitinated by Su(dx) and Cbl. RNAi-mediated knockdown in the larval brain neuroblasts abolishes the expression of pnt, induces the ectopic expression of erm, results in the ectopic expression of Ase in type II neuroblasts (NBs) and their premature loss (PubMed:18342578, PubMed:23056424, PubMed:27151950). Simultaneous RNAi-mediated knockdown of pnt partially restores normal neuroblast numbers and inhibits ectopic erm expression (PubMed:27151950). Belongs to the NOTCH family.