Structural domains comprising this superfamily share the structure of the ARF1-directed GTPase-activating protein, the cycle control GTPase activating protein (GAP) GCS1 which is important for the regulation of the ADP ribosylation factor ARF, a member of the Ras superfamily of GTP-binding proteins PMID:9446556. The GTP-bound form of ARF is required to maintain normal Golgi morphology, it participates in recruitment of coat proteins which are required for budding and fission of membranes. Hydrolysis of ARF-GTP promotes uncoating and fusion with an acceptor compartment. Before the fusion with an acceptor compartment the membrane must be uncoated. This ARF-GAP domain display no obvious similarity to other GAP proteins.