Crystallization of importin alpha, the nuclear-import receptor

Crystals of recombinant importin alpha, the nuclear-import receptor, have b een obtained at two different pH conditions by vapour diffusion using sodiu m citrate as precipitant and dithiothreitol as an additive. At pH 4-5, the crystals have the symmetry of the trigonal space group P3(1)21 or P3(2)21 ( a = b = 78.0, c = 255.8 Angstrom, gamma = 120 degrees); at pH 6-7, the crys tals have the symmetry of the orthorhombic space group P2(1)2(1)2(1) (a = 7 8.5, b = 89.7, c = 100.5 Angstrom). In both cases, there is probably one mo lecule of importin ct in the asymmetric unit. At least one of the crystal f orms diffracts to a resolution higher than 3 Angstrom using the laboratory X-ray source; the crystals are suitable for crystal structure determination .