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. 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. Highest level in lung and spleen. Low level in heart, kidney, liver and pancreas. 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. The BAR domain mediates homodimerization, it can neither bind membrane nor impart curvature, but instead requires the neighboring PH domain to achieve these functions. Phosphorylation at Ser-554 by PKB is required for interaction with ITGB1, export of ITGB1 from recycling endosomes to the cell surface and ITGB1-dependent cell migration. Cells overexpressing ACAP1 show an accumulation of ITGB1 in recycling endosomes and inhibition of stimulation-dependent cell migration. Cells with reduced levels of ACAP1 or AKT1 and AKT2 show inhibition of stimulation-dependent cell migration. Cells overexpressing ACAP1 and PIP5K1C show formation of tubular structures derived from endosomal membranes. Extended N-terminus.