Plays a role in constitutive metalloproteinase (MMP) secretion from the trans Golgi network. May have important functions during vesicle biogenesis at certain cargo subdomains, which could be predominantly utilized by secreted MMPs, such as MMP7 and MMP2. Also involved in autophagy by regulating the starvation-dependent trafficking of ATG9A vesicles which deliver the phosphatidylinositol 4-kinase beta (PI4KB) to the autophagosome initiation site. Involved in phagophore growth during mitophagy by regulating ATG9A trafficking to mitochondria. In addition, plays a role in NF-kappa-B inhibition by interacting with IKBKB and IKBKG. Forms homodimers or heterodimers with ARFIP1. Interacts with RAC1. Specifically binds to GTP-bound ARF1 and ARF6, but binds to RAC1.GTP and RAC1.GDP with similar affinities. Interacts with ARL1. Interacts (via N-terminus) with IKBKB and IKBKG; these interactions inhibit activation of NF-kappa-B.