Ras proteins bind GDP/GTP and possess intrinsic GTPase activity. GTP + H2O = GDP + H(+) + phosphate Alternates between an inactive form bound to GDP and an active form bound to GTP. Activated by a guanine nucleotide-exchange factor (GEF) and inactivated by a GTPase-activating protein (GAP). Belongs to the small GTPase superfamily. Ras family.