Promotes guanine-nucleotide exchange on ARF1, ARF5 and ARF6. Promotes the activation of ARF factors through replacement of GDP with GTP. Plays an important role in membrane trafficking, during junctional remodeling and epithelial polarization, through regulation of ARF6 activity. Interacts with TRIM23 and CYTIP (PubMed:10748148, PubMed:11867758). Interacts (via coiled-coil domain) with FRMD4A (via coiled-coil domain) (By similarity). Interacts with FRMD4B (By similarity). Found in a complex with PARD3, CYTH1 and FRMD4A (By similarity). Interacts (via N-terminal domain) with INAVA (via N-terminal domain) (PubMed:29420262). Colocalized with TJP1 during epithelial polarization. Ubiquitous. Binds via its PH domain to the inositol head group of phosphatidylinositol 3,4,5-trisphosphate. Autoinhibited by its C-terminal basic region. Ubiquitinated by SCF(FBXW11) E3 ubiquitin-protein ligase complex. Ubiquitination induces proteasomal degradation.