Function: GTP-binding protein involved in protein trafficking; regulates endocytic recycling and cytoskeleton remodeling. May modulate vesicle budding and uncoating within the Golgi apparatus. Functions as an allosteric activator of the cholera toxin catalytic subunit, an ADP-ribosyltransferase. Involved in the regulation of dendritic spine development (By similarity). Contributes to the regulation of dendritic branching and filopodia extension.