Download MendeleyArchitecture of Crm1-Exportin 1 Suggests How Cooperativity is Achieved During Formation of a Nuclear Export Complex
Petosa, C., Schoehn, G., Askjaer, P., Bauer, U., Moulin, M., Steuerwald, U., Soler-Lopez, M., Baudin, F., Mattaj, I.W., Muller, C.W.(2004) Mol Cell 16: 761
- PubMed: 15574331
- DOI: https://doi.org/10.1016/j.molcel.2004.11.018
- Primary Citation of Related Structures:
1W9C - PubMed Abstract:
CRM1/Exportin1 mediates the nuclear export of proteins bearing a leucine-rich nuclear export signal (NES) by forming a cooperative ternary complex with the NES-bearing substrate and the small GTPase Ran. We present a structural model of human CRM1 based on a combination of X-ray crystallography, homology modeling, and electron microscopy. The architecture of CRM1 resembles that of the import receptor transportin1, with 19 HEAT repeats and a large loop implicated in Ran binding. Residues critical for NES recognition are identified adjacent to the cysteine residue targeted by leptomycin B (LMB), a specific CRM1 inhibitor. We present evidence that a conformational change of the Ran binding loop accounts for the cooperativity of Ran- and substrate binding and for the selective enhancement of CRM1-mediated export by the cofactor RanBP3. Our findings indicate that a single architectural and mechanistic framework can explain the divergent effects of RanGTP on substrate binding by many import and export receptors.
Organizational Affiliation:
European Molecular Biology Laboratory, Grenoble Outstation, B.P. 181, 38042 Grenoble Cedex 9, France.
