Once inactivated by a GTPase-activating protein (GAP), GDP–Rabs are removed from ... activated by a guanine nucleotide-exchange factor (GEF). After the active Rab has carried out its function ...

Small G proteins (for example, Arfs) are activated when guanine nucleotide exchange factors (GEFs; for example, ARNO) catalyse the exchange of GDP for GTP. This process involves G-protein–GDP ...