Karyopherin alpha2 (KPNA2) is a member of the karyopherin alpha family. This protein plays a key role in the nuclear import of proteins with a classical nuclear localization signal (NLS). KPNA2 bound in vitro specifically and directly to substrates containing either a simple or bipartite NLS motif. It promoted docking of import substrates to the nuclear envelope and together with recombinant human Ran reconstituted complete nuclear protein import.