PURIFICATION, FUNCTIONAL-CHARACTERIZATION, AND CRYSTALLIZATION OF THE LIGAND-BINDING DOMAIN OF THE RETINOID-X RECEPTOR

The ligand binding domain (LED) of the human retinoid X receptor alpha (hRXR alpha) was overproduced in Escherichia coli and purified to more than 95% purity and functional homogeneity. Circular dichroism spectra of the purified RXR alpha LBD indicated that the protein was composed predominantly of cy-helical structures and coils, Crystals were grown from ammonium citrate using the vapor diffusion method against st reservoir containing 100 mM Pipes (pH 7.0) and 1.5 as ammonium citrate. They belong to the hexagonal space group P6(3)22 with unit cell parameters a = b = 110.8 Angstrom and c = 109.9 Angstrom, alpha = beta = 90 degrees, gamma = 120 degrees, and they diffract X rays to a resolution limit of 2.5 Angstrom using synchrotron radiation. The asymmetric unit of the crystals contains one molecule with a solvent content of approximately 55% and a V-m value of 3.6 Angstrom(3)/dalton. (C) 1995 Academic Press, Inc.