Crystallization of Nuclear Export Signals or Small-Molecule Inhibitors Bound to Nuclear Exporter CRM1

The Karyopherin protein CRM1 or XPO1 is the major nuclear export receptor that regulates nuclear exit of thousands of macromolecules in the cell. CRM1 recognizes protein cargoes by binding to their 8–15 residue-long nuclear export signals (NESs). A ternary CRM1–Ran–RanBP1 complex engineered to be suitable for crystallization has enabled structure determination by X-ray crystallography of CRM1 bound to many NES peptides and small-molecule inhibitors. Here, we present a protocol for the purification of the individual proteins, formation of the ternary CRM1–Ran–RanBP1 complex and crystallization of this complex for X-ray crystallography.