1gcj
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(New page: 200px<br /><applet load="1gcj" size="450" color="white" frame="true" align="right" spinBox="true" caption="1gcj, resolution 2.6Å" /> '''N-TERMINAL FRAGMENT O...)
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Revision as of 13:49, 20 November 2007
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N-TERMINAL FRAGMENT OF IMPORTIN-BETA
Overview
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.
About this Structure
1GCJ is a Single protein structure of sequence from Mus musculus. Full crystallographic information is available from OCA.
Reference
The adoption of a twisted structure of importin-beta is essential for the protein-protein interaction required for nuclear transport., Lee SJ, Imamoto N, Sakai H, Nakagawa A, Kose S, Koike M, Yamamoto M, Kumasaka T, Yoneda Y, Tsukihara T, J Mol Biol. 2000 Sep 8;302(1):251-64. PMID:10964573
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