We have cloned and expressed in Escherichia coli cDNA for rat nuclear transport factor 2 (NTF2), a key cytoplasmic factor that facilitates the import of proteins into the nucleus through nuclear pores, We have used this bacterially expressed material to produce orthorhombic crystals suitable for high-resolution X-ray diffraction structure determination. The crystals have P2(1)2(1)2(1) symmetry with a = 55.9 Angstrom; b = 56.7 Angstrom; c = 88.3 Angstrom and diffract past 2 Angstrom on laboratory X-ray sources. The asymmetric unit of these crystals contains two NTF2 polypeptide chains, consistent with the reported dimeric structure of the molecule. (C) 1996 Academic Press, Inc.