PURIFICATION, FUNCTIONAL-CHARACTERIZATION, AND CRYSTALLIZATION OF THELIGAND-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 mor e than 95% purity and functional homogeneity. Circular dichroism spect ra of the purified RXR alpha LBD indicated that the protein was compos ed predominantly of cy-helical structures and coils, Crystals were gro wn from ammonium citrate using the vapor diffusion method against st r eservoir 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 param eters a = b = 110.8 Angstrom and c = 109.9 Angstrom, alpha = beta = 90 degrees, gamma = 120 degrees, and they diffract X rays to a resolutio n limit of 2.5 Angstrom using synchrotron radiation. The asymmetric un it of the crystals contains one molecule with a solvent content of app roximately 55% and a V-m value of 3.6 Angstrom(3)/dalton. (C) 1995 Aca demic Press, Inc.