Karyopherin (KPNB1) Antibody – Goat

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. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Feb 2013]

KPNB1: a nuclear import protein nuclear protein import that functions either in association with an adapter protein, like an importin-alpha subunit, which binds to nuclear localization signals (NLS) in cargo substrates, or by acting as autonomous nuclear transport receptor. Acting autonomously, serves itself as NLS receptor. Docking of the importin/substrate complex to the nuclear pore complex (NPC) is mediated by KPNB1 through binding to nucleoporin FxFG repeats 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 importin-beta and the three components separate and importin-alpha and -beta are re- exported from the nucleus to the cytoplasm where GTP hydrolysis releases Ran from importin. 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. Mediates autonomously the nuclear import of ribosomal proteins RPL23A, RPS7 and RPL5. Binds to a beta-like import receptor binding (BIB) domain of RPL23A. In association with IPO7 mediates the nuclear import of H1 histone. In vitro, mediates nuclear import of H2A, H2B, H3 and H4 histones. In case of HIV-1 infection, binds and mediates the nuclear import of HIV-1 Rev. Imports PRKCI into the nucleus. Forms a complex with an importin alpha subunit. Forms a heterodimer with IPO7. Interacts with IPO7, SNUPN, RPL23A and XPO1. Two isoforms of the human protein have been reported. Belongs to the importin beta family.

Protein type: Nuclear import; Karyopherin

Chromosomal Location of Human Ortholog: 17q21.32

Cellular Component: cytoplasm; cytosol; membrane; nuclear envelope; nuclear membrane; nuclear pore; nucleoplasm; protein complex

Molecular Function: enzyme binding; Hsp90 protein binding; nuclear localization sequence binding; protein binding; protein domain specific binding; protein transporter activity; Ran GTPase binding; zinc ion binding

Biological Process: astral microtubule organization and biogenesis; DNA fragmentation during apoptosis; establishment of mitotic spindle localization; establishment of protein localization; mitotic chromosome movement towards spindle pole; mitotic metaphase plate congression; modification by virus of host cellular process; NLS-bearing substrate import into nucleus; protein import into nucleus; protein import into nucleus, docking; protein import into nucleus, translocation; Ran protein signal transduction; ribosomal protein import into nucleus