1QBK

STRUCTURE OF THE KARYOPHERIN BETA2-RAN GPPNHP NUCLEAR TRANSPORT COMPLEX

Summary for 1QBK

• Entry DOI: 10.2210/pdb1qbk/pdb
• Descriptor: KARYOPHERIN BETA2, RAN, MAGNESIUM ION, ... (4 entities in total)
• Functional Keywords: heat repeats, nuclear transport protein complex
• Biological source: Homo sapiens (human); More
• Cellular location: Cytoplasm: Q92973; Nucleus : P62826
• Total number of polymer chains: 2
• Total formula weight: 127665.20

Authors

Chook, Y.M.,Blobel, G. (deposition date: 1999-04-23, release date: 1999-06-01, Last modification date: 2024-10-30)

Primary citation

Chook, Y.M.,Blobel, G.
Structure of the nuclear transport complex karyopherin-beta2-Ran x GppNHp.
Nature, 399:230-237, 1999

PubMed Abstract: 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.

PubMed: 10353245
DOI: 10.1038/20375

Experimental method

X-RAY DIFFRACTION (3 Å)