GTPase-activating protein (GAP) for ADP ribosylation factor 6 (ARF6) required for clathrin-dependent export of proteins from recycling endosomes to trans-Golgi network and cell surface. Required for regulated export of ITGB1 from recycling endosomes to the cell surface and ITGB1-dependent cell migration (By similarity). GAP activity stimulated by phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidic acid. Banana-shaped homodimer laterally assembling into tetramers, the tetramers further pack helically onto the membrane. Interacts with GTP-bound ARF6. Interacts with third cytoplasmic loop of SLC2A4/GLUT4. Interacts with CLTC. Interacts with GULP1. Forms a complex with GDP-bound ARF6 and GULP1. Interacts with ITGB1; required for ITGB1 recycling. PH domain binds phospholipids including phosphatidic acid, phosphatidylinositol 3-phosphate, phosphatidylinositol 3,5-bisphosphate (PIP2) and phosphatidylinositol 3,4,5-trisphosphate (PIP3). May mediate ACAP1-binding to PIP2 or PIP3 containing membranes. Only one PH domain of one ACAP1 dimer inserts into the membrane, while the other PH domain acts primaryly to interact with adjacent ACAP1 dimers (By similarity). The BAR domain mediates homodimerization, it can neither bind membrane nor impart curvature, but instead requires the neighboring PH domain to achieve these functions (By similarity). Cells overexpressing Acap1 show accumulation of an electron dense coat containing Acap1 and Cltc on internal membranes as well as accumulation of Tfrc in pericentriolar recycling endosomes. Adipocytes with reduced level of Acap1 or Cltc fail to transport SLC2A4/GLUT4 from recycling endosomes to the cell surface upon insulin stimulation.