Small GTPase. Negatively regulates the transcription regulation activity of the APBB1/FE65-APP complex via its interaction with APBB1/FE65. Forms a ternary complex with CAPON and NOS1. Component of a complex, at least composed of APBB1, RASD1/DEXRAS1 and APP. Interacts with APBB1/FE65. Forms. Prominently found in brain at both mRNA and protein levels. Moderate expression in testis and lung. Slightly expressed in heart, spleen, skeletal muscle, liver and kidney. S-nitrosylation stimulates guanine-nucleotide exchange activity. Belongs to the small GTPase superfamily. RasD family.