ARF-family global interactome mapping uncovers spatial organization of cellular signaling pathways.

The ADP-ribosylation factor (ARF) family of GTPases are essential molecular switches that control a large variety of cellular processes. Here, we used classical proximity-dependent biotin identification (BioID) to comprehensively define the interactome of 28 out of 29 ARF proteins in two cell lines. The identification of ∼3000 high-confidence interactors allowed us to assign specific subcellular localization to the family members, uncovering previously undefined localization for ARL4D and ARL10. Clusterization analysis further showed the uniqueness in the set of interactors identified with these two ARF GTPases. We found that the expression of the understudied member ARL14 is restricted to the stomach and intestines and have identified phospholipase D1 (PLD1) and the ESCPE-1 complex, more precisely SNX1, as effectors. We showed that ARL14 can activate PLD1 in cellulo and is involved in the trafficking of cargos via the ESCPE-1 complex. Thus, the BioID data generated in this study represent a useful tool to dissect the intricacies of ARF signaling and its spatial organization.