GTP-binding protein involved in protein trafficking among different compartments (PubMed:11950392). Modulates vesicle budding and uncoating within the Golgi complex. Deactivation induces the redistribution of the entire Golgi complex to the endoplasmic reticulum, suggesting a crucial role in protein trafficking. In its GTP-bound form, its triggers the association with coat proteins with the Golgi membrane. The hydrolysis of ARF1-bound GTP, which is mediated by ARFGAPs proteins, is required for dissociation of coat proteins from Golgi membranes and vesicles. The GTP-bound form interacts with PICK1 to limit PICK1-mediated inhibition of Arp2/3 complex activity; the function is linked to AMPA receptor (AMPAR) trafficking, regulation of synaptic plasicity of excitatory synapses and spine shrinkage during long-term depression (LTD). Interacts (when activated) with GGA1, GGA2 and GGA3; the interaction is required for proper subcellular location of GGA1, GGA2 and GGA3 (PubMed:11950392, PubMed:12679809). Interacts with ARHGAP21, ASAP2, HERC1, PRKCABP, PIP5K1B, TMED2, PSCD2, TMED10 and GRIA2 (PubMed:17347647). Interacts with ARFGAP1, which hydrolyzes GTP and thus, regulates its function. Interacts with PI4KB in the Golgi complex. Interacts with NCS1/FREQ in the Golgi and at the plasma membrane. Interacts with PLEKHA3. Interacts with PLEKHA8; the interaction, together with phosphatidylinositol 4-phosphate binding, is required for FAPP2-mediated glucosylceramide transfer activity. Interacts (activated) with PICK1 (via PDZ domain); the interaction blocks Arp2/3 complex inhibition. Interacts with IQSEC1 (By similarity). Interacts with C9orf72 (PubMed:27723745) (By similarity). Belongs to the small GTPase superfamily. Arf family.