Crystallization of importin alpha, the nuclear-import receptor.

Crystals of recombinant importin alpha, the nuclear-import receptor, have been obtained at two different pH conditions by vapour diffusion using sodium citrate as precipitant and dithiothreitol as an additive. At pH 4-5, the crystals have the symmetry of the trigonal space group P3121 or P3221 (a = b = 78.0, c = 255.8 A, gamma = 120 degrees ); at pH 6-7, the crystals have the symmetry of the orthorhombic space group P212121 (a = 78.5, b = 89.7, c = 100.5 A). In both cases, there is probably one molecule of importin alpha in the asymmetric unit. At least one of the crystal forms diffracts to a resolution higher than 3 A using the laboratory X-ray source; the crystals are suitable for crystal structure determination.