importin 7; Ran-binding protein 7 (RanBP7, IPO7)

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Function

nuclear protein import as nuclear transport receptor
receptor for nuclear localization signals (NLS) in cargo substrates
thought to mediate docking of importin/substrate complex to the nuclear pore complex through binding to nucleoporin
the complex is subsequently translocated through the pore by an energy requiring, Ran-dependent mechanism
at the nucleoplasmic side of the nuclear pore complex, Ran binds to the importin, the importin/substrate complex dissociates & importin is re-exported from the nucleus to the cytoplasm where GTP hydrolysis releases Ran
directionality of nuclear import is thought to be conferred by an asymmetric distribution of the GTP- & GDP-bound forms of Ran between the cytoplasm & nucleus
mediates autonomously nuclear import of ribosomal proteins RPL23A, RPS7 & RPL5
binds to a beta-like import receptor binding (BIB) domain of RPL23A
forms heterodimer with KPNB1 (importin-beta-1-subunit)
in association with KPNB1 mediates the nuclear import of histone H1, Ran-binding site of IPO7 is not required but synergizes with that of KPNB1 in importin/substrate complex dissociation
in vitro, mediates nuclear import of H2A, H2B, H3 & H4 histones
interacts with H2A, H2B, H3 & H4 histones
forms a heterodimer with KPNB1
interacts with KPNB1, SNUPN, XPO1, RPL23A, RPS7, RPL5
binds directly to nuclear pore complexes

in vitro, mediates the nuclear import of HIV-1 reverse transcription complex integrase
in case of HIV-1 infection, binds & mediates nuclear import of HIV-1 Rev