1GCJ

N-TERMINAL FRAGMENT OF IMPORTIN-BETA

Summary for 1GCJ

• Entry DOI: 10.2210/pdb1gcj/pdb
• Related: 1IBR 1QGK 1QGR
• Descriptor: IMPORTIN BETA (2 entities in total)
• Functional Keywords: heat repeat motif, nuclear pore-targeting complex component, nuclear import factor, transport protein
• Biological source: Mus musculus (house mouse)
• Total number of polymer chains: 2
• Total formula weight: 103757.47

Authors

Lee, S.J.,Imamoto, N.,Sakai, H.,Nakagawa, A.,Kose, S.,Koike, M.,Yamamoto, M.,Kumasaka, T.,Yoneda, Y.,Tsukihara, T. (deposition date: 2000-07-31, release date: 2000-10-18, Last modification date: 2024-10-16)

Primary citation

Lee, S.J.,Imamoto, N.,Sakai, H.,Nakagawa, A.,Kose, S.,Koike, M.,Yamamoto, M.,Kumasaka, T.,Yoneda, Y.,Tsukihara, T.
The adoption of a twisted structure of importin-beta is essential for the protein-protein interaction required for nuclear transport.
J.Mol.Biol., 302:251-264, 2000

PubMed Abstract: Importin-beta is a nuclear transport factor which mediates the nuclear import of various nuclear proteins. The N-terminal 1-449 residue fragment of mouse importin-beta (impbeta449) possesses the ability to bidirectionally translocate through the nuclear pore complex (NPC), and to bind RanGTP. The structure of the uncomplexed form of impbeta449 has been solved at a 2.6 A resolution by X-ray crystallography. It consists of ten copies of the tandemly arrayed HEAT repeat and exhibits conformational flexibility which is involved in protein-protein interaction for nuclear transport. The overall conformation of the HEAT repeats shows that a twisted motion produces a significantly varied superhelical architecture from the previously reported structure of RanGTP-bound importin-beta. These conformational changes appear to be the sum of small conformational changes throughout the polypeptide. Such a flexibility, which resides in the stacked HEAT repeats, is essential for interaction with RanGTP or with NPCs. Furthermore, it was found that impbeta449 has a structural similarity with another nuclear migrating protein, namely beta-catenin, which is composed of another type of helix-repeated structure of ARM repeat. Interestingly, the essential regions for NPC translocation for both importin-beta and beta-catenin are spatially well overlapped with one another. This strongly indicates the importance of helix stacking of the HEAT or ARM repeats for NPC-passage.

PubMed: 10964573
DOI: 10.1006/jmbi.2000.4055

Experimental method

X-RAY DIFFRACTION (2.6 Å)