CorC is a magnesium transporter that is involved in the Mg(2+)-efflux function of the CorA transporter system, an Mg(2+) channel, from Shigella flexneri. Native CorC was purified and crystallized in the native form and in a ligand-free form and diffraction data sets were collected to 2.9 and 3.4 A resolution, respectively. The native CorC crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 64.31, b = 74.44, c = 132.78 A. The ligand-free CorC crystals belonged to space group P3(1)21/P3(2)21, with unit-cell parameters a = b = 71.89, c = 125.96 A. The CorC-ATP complex has also been crystallized and the crystals belonged to space group P2 or P2(1).