GTP-binding protein involved in protein trafficking; required for the sequence-specific vacuolar sorting route to the lytic vacuole, for the ER-to-Golgi transport and for the Golgi-derived transport to the plasma membrane (PubMed:24369434). Involved in the recruitment of COPI and GDAP1 to membranes. Required for recycling of PIN auxin transporters (e.g. PIN1 and PIN2) in a fungal toxin brefeldin A (BFA)-dependent manner. Involved in various auxin-dependent developmental processes (PubMed:24369434). Activated by AGD7 and AGD10. Interacts with AGD7 and GDAP1. GDP-locked form interacts with cytosolic tail of p24 proteins. Interacts with AGD5 at trans-Golgi network (PubMed:21105926). Interacts with A.tumefaciens AK6b (PubMed:21156810). Colocalizes with AGD5 at trans-Golgi network. Belongs to the small GTPase superfamily. Arf family.