Crystal Structure of the Nuclear Export Receptor CRM1 in Complex with Snurportin1 and RanGTP

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Science  22 May 2009:
Vol. 324, Issue 5930, pp. 1087-1091
DOI: 10.1126/science.1173388

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CRM1 mediates nuclear export of numerous unrelated cargoes, which may carry a short leucine-rich nuclear export signal or export signatures that include folded domains. How CRM1 recognizes such a variety of cargoes has been unknown up to this point. Here we present the crystal structure of the SPN1⋅CRM1⋅RanGTP export complex at 2.5 angstrom resolution (where SPN1 is snurportin1 and RanGTP is guanosine 5′ triphosphate–bound Ran). SPN1 is a nuclear import adapter for cytoplasmically assembled, m3G-capped spliceosomal U snRNPs (small nuclear ribonucleoproteins). The structure shows how CRM1 can specifically return the cargo-free form of SPN1 to the cytoplasm. The extensive contact area includes five hydrophobic residues at the SPN1 amino terminus that dock into a hydrophobic cleft of CRM1, as well as numerous hydrophilic contacts of CRM1 to m3G cap-binding domain and carboxyl-terminal residues of SPN1. The structure suggests that RanGTP promotes cargo-binding to CRM1 solely through long-range conformational changes in the exportin.

  • * These authors contributed equally to this work.

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