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

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 Structure: - belongs to the importin beta family - contains 8 HEAT repeats - contains 1 importin N-terminal domain Compartment: cytoplasm, nucleus envelope Pathology: - in case of HIV-1 infection, binds & mediates the nuclear import of HIV-1 Rev - binds to HIV-1 Rev & Tat - interacts with HTLV-1 Rex

Properties

SIZE: entity length = 876 aa MW = 97 kD COMPARTMENT: cytoplasm cell nucleus MOTIF: acetylation site SITE: 1-1 EFFECTOR-BOUND: acetyl Importin N-terminal {21-101} HEAT repeat {124-163} HEAT repeat {168-207} HEAT repeat {213-250} HEAT repeat {317-357} MOTIF: binding site SITE: 329-342 FOR-BINDING-OF: IAB Ran-GTP binding {334-419} MOTIF: HEAT repeat {362-399} HEAT repeat {404-441} HEAT repeat {602-641} HEAT repeat {687-726}

Database Correlations

OMIM 602738 UniProt Q14974 PFAM correlations Entrez Gene 3837 Kegg hsa:3837

References

UniProt :accession Q14974