transportin-2; karyopherin beta-2b (TNPO2)

Function

• role in nuclear protein import as nuclear transport receptor
• serves as receptor for nuclear localization signals (NLS) in cargo substrates
• thought to mediate docking of the importin/substrate complex to the nuclear pore complex (NPC) 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 NPC, Ran binds to importin, the importin/substrate complex dissociates & 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- & GDP- bound forms of Ran between the cytoplasm & nucleus (putative)

Structure

• belongs to the importin beta family
• contains 13 HEAT repeats
• contains 1 importin N-terminal domain

Compartment

• cytoplasm (putative), nucleus

Alternative splicing

named isoforms=2

More general terms

• transportin (TNPO)
• nuclear protein
• HEAT repeat-containing protein (HEATR)

Additional terms

• importin beta-2 subunit (karyopherin beta-2 subunit, KPNB2, transportin-1, M9 region interaction protein, MIP, TNPO1, MIP1, TRN)

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=30000
• OMIM: https://mirror.omim.org/entry/603002
• UniProt: http://www.uniprot.org/uniprot/O14787.html