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'''STRUCTURE OF THE KARYOPHERIN BETA2-RAN GPPNHP NUCLEAR TRANSPORT COMPLEX''' | '''STRUCTURE OF THE KARYOPHERIN BETA2-RAN GPPNHP NUCLEAR TRANSPORT COMPLEX''' | ||
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[[Category: Blobel, G.]] | [[Category: Blobel, G.]] | ||
[[Category: Chook, Y M.]] | [[Category: Chook, Y M.]] | ||
[[Category: | [[Category: Heat repeat]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 06:06:09 2008'' | |||
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Revision as of 03:06, 3 May 2008
STRUCTURE OF THE KARYOPHERIN BETA2-RAN GPPNHP NUCLEAR TRANSPORT COMPLEX
Overview
Transport factors in the karyopherin-beta (also called importin-beta) family mediate the movement of macromolecules in nuclear-cytoplasmic transport pathways. Karyopherin-beta2 (transportin) binds a cognate import substrate and targets it to the nuclear pore complex. In the nucleus, Ran x GTP binds karyopherin-beta2 and dissociates the substrate. Here we present the 3.0 A structure of the karyopherin-beta2-Ran x GppNHp complex where GppNHp is a non-hydrolysable GTP analogue. Karyopherin-beta2 contains eighteen HEAT repeats arranged into two continuous orthogonal arches. Ran is clamped in the amino-terminal arch and substrate-binding activity is mapped to the carboxy-terminal arch. A large loop in HEAT repeat 7 spans both arches. Interactions of the loop with Ran and the C-terminal arch implicate it in GTPase-mediated dissociation of the import-substrate. Ran x GppNHp in the complex shows extensive structural rearrangement, compared to Ran GDP, in regions contacting karyopherin-beta2. This provides a structural basis for the specificity of the karyopherin-beta family for the GTP-bound state of Ran, as well as a rationale for interactions of the karyopherin-Ran complex with the regulatory proteins ranGAP, ranGEF and ranBP1.
About this Structure
1QBK is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Structure of the nuclear transport complex karyopherin-beta2-Ran x GppNHp., Chook YM, Blobel G, Nature. 1999 May 20;399(6733):230-7. PMID:10353245 Page seeded by OCA on Sat May 3 06:06:09 2008
