Small GTPase required for proper localization of RNA polymerase II (RNAPII). May act at an RNAP assembly step prior to nuclear import. Heterodimer with GPN1. Binds to RNA polymerase II (RNAPII). Interacts directly with subunits RPB4 and RPB7 and the CTD of RPB1. Belongs to the GPN-loop GTPase family.