GTPase-activating protein (GAP) for ADP ribosylation factor (ARF). Involved in the spatial control of provascular differentiation. Required for the formation of the normal pattern of continuous secondary veins. Involved in auxin signaling but not in polar auxin transport or in auxin responses. Required for PIN1 internalization in roots. ARF GAP activity strongly enhanced by phosphatidylinositol 4-monophosphate (PIP) and moderately enhanced by phosphatidylinositol 4,5-bisphosphate (PIP2). Homodimer (PubMed:15743878). Interacts with DRP1A (PubMed:15923323). Interacts with VAB (PubMed:19363154). BAR and PH domains are essential for the proper localization. Localization seems to be regulated by CVP2 and CVL1 activity as the phosphatidylinositol 4-monophosphate (PIP)-binding by the PH domain is required for the TGN localization. Broadly expressed. Detected in developing veins of the leaf and root (PubMed:19473324). Detected in roots, hypocotyls, cotyledons, leaves, siliques and shoot apical meristems (PubMed:16698946). Expression refined to procambial cells during embryogenesis. Up-regulated by auxin. The PH domain is responsive of the binding to phosphoinositol (PubMed:19473324). The BAR domain is required and sufficient for homodimerization (PubMed:15743878). Binds to phosphatidylinositol (PI), phosphatidylinositol 4-monophosphate (PIP) and phosphatidylinositol 4,5-bisphosphate (PIP2) but not to phosphatidic acid (PA), phosphatidylcholine (PC) or phosphatidylethanolamine (PE).