GTPase-activating protein (GAP) for ADP ribosylation factor (ARF). Activates ARF1 and ARF2. Required for female gametophyte development. Involved in root hair and pollen tube growth. Expressed specifically in roots, pollen grains and pollen tubes. The C-terminal domain (317-395) is responsible for the Golgi localization. Plants are arrested during endosperm development and have altered root hair development and pollen tube elongation.