GTPase signaling protein that binds to and hydrolyzes GTP. Regulates signaling pathways involving G-proteins-coupled receptor and heterotrimeric proteins such as GNB1, GNB2 and GNB3. May be involved in selected striatal competencies, mainly locomotor activity and motor coordination. Monomer (Potential). Interacts with GNB1, GNB2 and GNB3 (By similarity). Interacts with PIK3CA and UBE2I. Found in granular structures throughout the cytosol. Prominently expressed in the striatum, weakly in the cerebral cortex and the CA fields of the hippocampus. Highly expressed in the hippocampus and cerebellum, only during the postnatal period. Also expressed in pancreatic endocrine cells (islets of Langerhans), adrenal gland and stomach and in a thyroid cell line. Low levels detected at E16 through P10, and increased between P10 and P15 during the development of brain; the amount did decrease in the adult brain. By thyroid hormone, efaroxan and glibenclamide. Farnesylated. Farnesylation is required for membrane targeting. Belongs to the small GTPase superfamily. RasD family.