Crystallization of the flexible nuclear import receptor importin-β in the unliganded state

The transport of macromolecules across the nuclear envelope is an essential eukaryotic process that enables proteins such as transcription factors, poly­merases and histones to gain access to the genetic material contained within the nucleus. Importin-β plays a central role in the nucleocytoplasmic transport process, mediating nuclear import through a range of interactions with cytoplasmic, nuclear and nuclear pore proteins such as importin-α, Ran, nucleo­porins and various cargo molecules. The unliganded form of the full-length yeast importin-­β has been expressed and crystallized. The crystals were obtained by vapour diffusion at pH 6.5 and 290 K. The crystals belonged to space group P2₁ (unit-cell parameters a = 58.17, b = 127.25, c = 68.52 Å, β = 102.23). One molecule is expected in the asymmetric unit. The crystals diffracted to 2.4 Å resolution using a laboratory X-ray source and were suitable for crystal structure determination.