Activator of the NOTCH1 pathway. May mediate neuron-glia interaction during astrocytogenesis (By similarity). Interacts with AP1G1. Interacts with NOTCH1 (By similarity). Present on the membrane of dendrites and cell bodies but excluded from axonal membrane. Also found in early endosomes in the somatodendritic region (By similarity). Expressed in brain, spinal cord and adrenal gland.