Plays a role in hippocampal-dependent synaptic plasticity, learning and memory. Involved in the formation of spines and functional synaptic contacts by modulating the translational activity of the cytoplasmic polyadenylation element-binding protein CPEB3. Promotes ubiquitination of CPEB3, and hence induces CPEB3-dependent mRNA translation activation of glutamate receptor GRIA1 and GRIA2. Can function as an E3 ubiquitin-protein ligase to activate monoubiquitination of JAG1 (in vitro), thereby regulating the Notch pathway. Acts as a tumor suppressor; inhibits malignant cell transformation of medulloblastoma (MB) cells by inhibiting the Notch signaling pathway. 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. Interacts with CPEB3 (via N-terminal domain); the interaction increases CPEB3 ubiquitination. Interacts with DLL1 (PubMed:19723503). Colocalized with JAG1 at the cell surface (By similarity). Localized in the cell bodies of the pyramidal neurons and distributed along their apical dendrites. Colocalized with PSD95 in postsynaptic sites. Colocalized with CPEB3 at apical dendrites of CA1 neurons. Expressed in CA1 pyramidal neurons (at protein level). Expressed throughout the adult forebrain, including the cerebral cortex, amygdala, striatum, and CA1 area of the hippocampus. Expressed in sensory neurons of the olfactory epithelium, the vomeronasal organ, mammary gland and skeletal muscle. Expressed in the somites at 8.5 dpc onwards. Up-regulated by synaptic activity. Myristoylation is a determinant of membrane targeting. According to PubMed:11585928, knockout male mice lacking Neurl1 are sterile due to a defect in axoneme organization in the spermatozoa that leads to compromised tail movement and sperm motility; knockout female mice lacking Neurl1 are defective in the final stages of mammary gland maturation during pregnancy. According to PubMed:11481456 knockout mice lacking Neurl1 are viable and morphologically normal but display an olfactory discrimination and are more sensitive to the effect of ethanol on motor coordination.