1ukl

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Crystal structure of Importin-beta and SREBP-2 complex

Structural highlights

1ukl is a 6 chain structure with sequence from Homo sapiens and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 3Å
Ligands:MSE
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

IMB1_MOUSE Functions in nuclear protein import, 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 (By similarity).[1]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

The sterol regulatory element-binding protein 2 (SREBP-2), a nuclear transcription factor that is essential for cholesterol metabolism, enters the nucleus through a direct interaction of its helix-loop-helix leucine zipper domain with importin-beta. We show the crystal structure of importin-beta complexed with the active form of SREBP-2. Importin-beta uses characteristic long helices like a pair of chopsticks to interact with an SREBP-2 dimer. Importin-beta changes its conformation to reveal a pseudo-twofold symmetry on its surface structure so that it can accommodate a symmetric dimer molecule. Importin-beta may use a similar strategy to recognize other dimeric cargoes.

The structure of importin-beta bound to SREBP-2: nuclear import of a transcription factor.,Lee SJ, Sekimoto T, Yamashita E, Nagoshi E, Nakagawa A, Imamoto N, Yoshimura M, Sakai H, Chong KT, Tsukihara T, Yoneda Y Science. 2003 Nov 28;302(5650):1571-5. PMID:14645851[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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Citations
31 reviews cite this structure
SREBP transcription factors: master regulators of lipid homeostasis.
Eberlé et al. (2004)
30 more
97 other articles
No citations found

See Also

References

  1. ↑ Muhlhausser P, Muller EC, Otto A, Kutay U. Multiple pathways contribute to nuclear import of core histones. EMBO Rep. 2001 Aug;2(8):690-6. PMID:11493596 doi:http://dx.doi.org/10.1093/embo-reports/kve168
  2. ↑ Lee SJ, Sekimoto T, Yamashita E, Nagoshi E, Nakagawa A, Imamoto N, Yoshimura M, Sakai H, Chong KT, Tsukihara T, Yoneda Y. The structure of importin-beta bound to SREBP-2: nuclear import of a transcription factor. Science. 2003 Nov 28;302(5650):1571-5. PMID:14645851 doi:10.1126/science.1088372

Contents


PDB ID 1ukl

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