GPN-loop GTPase 1 （GPN1） is a member of the GPN-loop GTPase family. GPN1 is a guanosine triphosphatase enzyme which has a role in DNA repair and may function in activation of transcription. Small GTPases， which share a biochemical mechanism， act as binary molecular switches and function in the cell is nucleocytoplasmic transport of both proteins and RNA. In addition， GPN1 establishs an interface between the RNA polymerase II enzyme and chaperone/scaffolding protein， proposing that it is essential to connect RNA polymerase II to regulators of protein complex formation. GPN1 may also be involved in nuclear localization of XPA.
