Promotes guanine-nucleotide exchange on ARF1 and ARF6. Promotes the activation of ARF factors through replacement of GDP with GTP. Plays a role in the epithelial polarization (By similarity). Interacts with TAMALIN (By similarity). Interacts with ARF6 (PubMed:23940353). Interacts with FRMD4A (By similarity). Interacts with FRMD4B (By similarity). Translocates from the cytosol to membranes enriched in phosphatidylinositol 3,4,5-trisphosphate. Almost absent from liver, thymus and peripheral blood lymphocytes. Binds via its PH domain to the inositol head group of phosphatidylinositol 3,4,5-trisphosphate. Autoinhibited by its C-terminal basic region.