Guanine nucleotide exchange factor for ARF1 and ARF6. Guanine nucleotide exchange factor activity is enhanced by lipid binding. Accelerates GTP binding by ARFs of all three classes. Guanine nucleotide exchange protein for ARF6, mediating internalization of beta-1 integrin (By similarity). Involved in neuronal development (PubMed:31607425). In neurons, plays a role in the control of vesicle formation by endocytoc cargo. Upon long term depression, interacts with GRIA2 and mediates the activation of ARF6 to internalize synaptic AMPAR receptors (By similarity). Interacts with ARF1 and ARF6. Interacts with GRIA2; the interaction is required for ARF6 activation. At steady state, may be preferentially cytosolic. Expressed in hippocampus. Expression is first detected at postanatal day P7 and increases until P42 (at protein level). The PH domain mediates interaction with lipid membranes that contain phosphatidylinositol-4,5-bisphosphate, but does not bind membranes that lack phosphatidylinositol-4,5-bisphosphate. Mice with a conditional knockout in cortical neurons exhibit an increased density of dendritic spines with an immature morphology. Belongs to the BRAG family.