| Structural highlights
4jlq is a 2 chain structure with sequence from Baker's yeast and Human. This structure supersedes the now removed PDB entry 4h1k. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Gene: | KPNB2, MIP1, TNPO1, TRN (HUMAN), NAB2, YGL122C (Baker's yeast) |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT |
Function
[TNPO1_HUMAN] 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). Involved in nuclear import of M9-containing proteins. In vitro, binds directly to the M9 region of the heterogeneous nuclear ribonucleoproteins (hnRNP), A1 and A2 and mediates their nuclear import. Appears also to be involved in hnRNP A1/A2 nuclear export. 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, and SRP19. In case of HIV-1 infection, binds and mediates the nuclear import of HIV-1 Rev. Mediates nuclear import of ADAR/ADAR1 (isoform 5) in a RanGTP-dependent manner.[1] [2] [3] [4] [NAB2_YEAST] This essential protein binds to polyadenylated RNA and single-stranded DNA. It may be involved not only in RNA processing but also in transcription regulation. Believed to associate directly with nascent RNA polymerase II transcripts and remain associated during subsequent nuclear RNA processing reactions.
Publication Abstract from PubMed
Import-Karyopherin or Importin proteins bind nuclear localization signals (NLSs) to mediate the import of proteins into the cell nucleus. Karyopherin beta2 or Kapbeta2, also known as Transportin, is a member of this transporter family responsible for the import of numerous RNA binding proteins. Kapbeta2 recognizes a targeting signal termed the PY-NLS that lies within its cargos to target them through the nuclear pore complex. The recognition of PY-NLS by Kapbeta2 is conserved throughout eukaryotes. Kap104, the Kapbeta2 homolog in Saccharomyces cerevisiae, recognizes PY-NLSs in cargos Nab2, Hrp1, and Tfg2. We have determined the crystal structure of Kapbeta2 bound to the PY-NLS of the mRNA processing protein Nab2 at 3.05-A resolution. A seven-residue segment of the PY-NLS of Nab2 is observed to bind Kapbeta2 in an extended conformation and occupies the same PY-NLS binding site observed in other Kapbeta2.PY-NLS structures.
Crystal structure of human Karyopherin beta2 bound to the PY-NLS of Saccharomyces cerevisiae Nab2.,Soniat M, Sampathkumar P, Collett G, Gizzi AS, Banu RN, Bhosle RC, Chamala S, Chowdhury S, Fiser A, Glenn AS, Hammonds J, Hillerich B, Khafizov K, Love JD, Matikainen B, Seidel RD, Toro R, Rajesh Kumar P, Bonanno JB, Chook YM, Almo SC J Struct Funct Genomics. 2013 Jun;14(2):31-5. doi: 10.1007/s10969-013-9150-1., Epub 2013 Mar 28. PMID:23535894[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Nakielny S, Siomi MC, Siomi H, Michael WM, Pollard V, Dreyfuss G. Transportin: nuclear transport receptor of a novel nuclear protein import pathway. Exp Cell Res. 1996 Dec 15;229(2):261-6. PMID:8986607 doi:10.1006/excr.1996.0369
- ↑ Jakel S, Gorlich D. Importin beta, transportin, RanBP5 and RanBP7 mediate nuclear import of ribosomal proteins in mammalian cells. EMBO J. 1998 Aug 3;17(15):4491-502. PMID:9687515 doi:10.1093/emboj/17.15.4491
- ↑ Dean KA, von Ahsen O, Gorlich D, Fried HM. Signal recognition particle protein 19 is imported into the nucleus by importin 8 (RanBP8) and transportin. J Cell Sci. 2001 Oct;114(Pt 19):3479-85. PMID:11682607
- ↑ Fritz J, Strehblow A, Taschner A, Schopoff S, Pasierbek P, Jantsch MF. RNA-regulated interaction of transportin-1 and exportin-5 with the double-stranded RNA-binding domain regulates nucleocytoplasmic shuttling of ADAR1. Mol Cell Biol. 2009 Mar;29(6):1487-97. doi: 10.1128/MCB.01519-08. Epub 2009 Jan, 5. PMID:19124606 doi:10.1128/MCB.01519-08
- ↑ Soniat M, Sampathkumar P, Collett G, Gizzi AS, Banu RN, Bhosle RC, Chamala S, Chowdhury S, Fiser A, Glenn AS, Hammonds J, Hillerich B, Khafizov K, Love JD, Matikainen B, Seidel RD, Toro R, Rajesh Kumar P, Bonanno JB, Chook YM, Almo SC. Crystal structure of human Karyopherin beta2 bound to the PY-NLS of Saccharomyces cerevisiae Nab2. J Struct Funct Genomics. 2013 Jun;14(2):31-5. doi: 10.1007/s10969-013-9150-1., Epub 2013 Mar 28. PMID:23535894 doi:10.1007/s10969-013-9150-1
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