This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1gcj
From Proteopedia
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 Page seeded by OCA on Fri May 2 17:24:54 2008
