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 (PubMed:21768307). Binds to RNA polymerase II (RNAPII) (PubMed:20864038, PubMed:21768307). Interacts directly with subunits RPB4 and RPB7 and the CTD of RPB1 (PubMed:21768307). Belongs to the GPN-loop GTPase family.