2Q5D: Crystal Structure Of Human Importin Beta Bound To The Snurportin1 Ibb- Domain Second Crystal Form

The nuclear import of uridine-rich ribonucleoproteins is mediated by the transport adaptor snurportin 1 (SNP1). Similar to importin alpha, SNP1 uses an N-terminal importin beta binding (sIBB) domain to recruit the receptor importin beta and gain access to the nucleus. In this study, we demonstrate that the sIBB domain has a bipartite nature, which contains two distinct binding determinants for importin beta. The first determinant spans residues 25-65 and includes the previously identified importin alpha IBB (alphaIBB) region of homology. The second binding determinant encompasses residues 1-24 and resembles region 1011-1035 of the nucleoporin 153 (Nup153). The two binding determinants synergize within the sIBB domain to confer a low nanomolar binding affinity for importin beta (K(d) approximately 2 nm) in an interaction that, in vitro, is displaced by RanGTP. We propose that in vivo the synergy of Nup153 and nuclear RanGTP promotes translocation of uridine-rich ribonucleoproteins into the nucleus.
PDB ID: 2Q5DDownload
MMDB ID: 61974
PDB Deposition Date: 2007/5/31
Updated in MMDB: 2009/07
Experimental Method:
x-ray diffraction
Resolution: 3.2  Å
Source Organism:
Similar Structures:
Biological Unit for 2Q5D: dimeric; determined by author
Molecular Components in 2Q5D
Label Count Molecule
Proteins (2 molecules)
Importin Beta-1 Subunit(Gene symbol: KPNB1)
Molecule annotation
Snurportin-1(Gene symbol: SNUPN)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB