Expression, purification, crystallization and preliminary X-ray diffraction analysis of chloride intracellular channel 2 (CLIC2)

The chloride intracellular channel (CLIC) family of proteins are unusual in that they can exist in either an integral membrane-channel form or a soluble form. Here, the expression, purification, crystallization and preliminary diffraction analysis of CLIC2, one of the least-studied members of this family, are reported. Human CLIC2 was crystallized in two different forms, both in the presence of reduced glutathione and both of which diffracted to better than 1.9 Å resolution. Crystal form A displayed P2₁2₁2₁ symmetry, with unit-cell parameters a = 44.0, b = 74.7, c = 79.8 Å. Crystal form B displayed P2₁ symmetry, with unit-cell parameters a = 36.0, b = 66.9, c = 44.1 Å. Structure determination will shed more light on the structure and function of this enigmatic family of proteins.