importin beta-1 subunit (karyopherin beta-1 subunit, KPNB1, nuclear factor P97, importin 90)

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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 the nuclear import of ribosomal proteins RPL23A, RPS7 & RPL5
binds to a beta-like import receptor binding (BIB) domain of RPL23A
forms a heterodimer with IPO7
in association with IPO7, mediates the nuclear import of H1 histone
in vitro, mediates nuclear import of H2A, H2B, H3 & H4 histones.
imports PRKCI into the nucleus
forms a complex with an importin alpha subunit
interacts with IPO7, SNUPN, RPL23A & XPO1
KPNB1/IPO7 heterodimer interacts with H1 histone
component of an import snRNP complex
component of a nuclear export receptor complex
interacts with SRY
interacts with PRKCI/atypical protein kinase C iota