Small GTPase required for proper nuclear import of RNA polymerase II (RNAPII). May act at an RNAP assembly step prior to nuclear import. Forms an interface between the RNA polymerase II enzyme and chaperone/scaffolding proteins, suggesting that it is required to connect RNA polymerase II to regulators of protein complex formation. May be involved in nuclear localization of XPA. Heterodimer with GPN3. Binds to RNA polymerase II (RNAPII). Interacts directly with RNAPII subunits RPB4 and RPB7 and the CTD of RPB1. Interacts with XPA. Shuttles between the nucleus and the cytoplasm. Belongs to the GPN-loop GTPase family.