The importin subunit beta-3 has a superhelical structure composed of tandem repeats structurally similar to HEAT repeats [1]. This Pfam entry includes a single repeat unit.

1: Structural basis for cell-cycle-dependent nuclear import mediated by the karyopherin Kap121p. Kobayashi J, Matsuura Y; J Mol Biol. 2013;425:1852-1868. PMID:23541588