DNER, also known as brain EGF repeat containing transmembrane protein (BET), is a neuron-specific type I transmembrane notch ligand that is expressed on membranes of dendrites and cell bodies but not axons. It contains ten extracellular EGF-like domains and one follistatin-like domain (between the 9th and 10th EGF-like domains). DNER mediates neuron-glia interactions and is required for the functional and morphological maturation of the cerebellum. The extracellular domains of human and mouse DNER share 89% amino acid sequence homology.