Acts as a guanine nucleotide exchange factor (GEF) for ARF1. Interacts with DLG1 and DLG4 (By similarity). Interacts with GPHN (By similarity). Expressed specifically in the adult brain, predominantly in the cerebral cortex and the olfactory bulb, but not in the fetal brain. Expressed only in mature neurons, but not in undifferentiated neural stem precursor cells (NSPCs), nor in glioma cells. Belongs to the BRAG family.