IPO5

Nucleocytoplasmic transport, a signal-and energy-dependent process, takes place through nuclear pore complexes embedded in the nuclear envelope. The import of proteins containing a nuclear localization signal (NLS) requires the NLS import receptor, a heterodimer of importin alpha and beta subunits also known as karyopherins. Importin alpha binds the NLS-containing cargo in the cytoplasm and importin beta docks the complex at the cytoplasmic side of the nuclear pore complex. In the presence of nucleoside triphosphates and the small GTP binding protein Ran, the complex moves into the nuclear pore complex and the importin subunits dissociate. Importin alpha enters the nucleoplasm with its passenger protein and importin beta remains at the pore. Interactions between importin beta and the FG repeats of nucleoporins are essential in translocation through the pore complex. The protein encoded by this gene is a member of the importin beta family.

Full Name

Importin 5

Function

Functions in nuclear protein import as nuclear transport receptor. Serves as receptor for nuclear localization signals (NLS) in cargo substrates. Is thought to mediate docking of the importin/substrate complex to the nuclear pore complex (NPC) through binding to nucleoporin and the complex is subsequently translocated through the pore by an energy requiring, Ran-dependent mechanism. At the nucleoplasmic side of the NPC, Ran binds to the importin, the importin/substrate complex dissociates and importin is re-exported from the nucleus to the cytoplasm where GTP hydrolysis releases Ran. The directionality of nuclear import is thought to be conferred by an asymmetric distribution of the GTP- and GDP-bound forms of Ran between the cytoplasm and nucleus (By similarity).
Mediates the nuclear import of ribosomal proteins RPL23A, RPS7 and RPL5. Binds to a beta-like import receptor binding (BIB) domain of RPL23A. In vitro, mediates nuclear import of H2A, H2B, H3 and H4 histones. Binds to CPEB3 and mediates its nuclear import following neuronal stimulation (By similarity).
In case of HIV-1 infection, binds and mediates the nuclear import of HIV-1 Rev.

Biological Process

Cellular response to amino acid stimulusISS:UniProtKB
Negative regulation of cyclin-dependent protein serine/threonine kinase activityManual Assertion Based On ExperimentTAS:ARUK-UCL
NLS-bearing protein import into nucleusISS:UniProtKB
Positive regulation of protein import into nucleusISS:UniProtKB
Protein import into nucleusManual Assertion Based On ExperimentIBA:GO_Central
Ribosomal protein import into nucleusManual Assertion Based On ExperimentIDA:UniProtKB

Cellular Location

Cytoplasm; Nucleus; Nucleus, nucleolus. Nucleus; nuclear rim. Found particularly in the nuclear rim and nucleolus.