Small GTPase required for proper nuclear localization of RNA polymerase II and III (RNAPII and RNAPIII). May act at an RNAP assembly step prior to nuclear import (PubMed:23267056). Promotes sister chromatid separation during anaphase (PubMed:23324351). Heterodimers with NPA3/GPN1 or GPN2 (PubMed:23324351, PubMed:23267056). Binds to RNA polymerase II (RNAPII) (By similarity). Belongs to the GPN-loop GTPase family.