Crystallization and preliminary X-ray diffraction analysis of the regulatory subunit of human protein kinase CK2

Protein kinase CK2 is a tetramer composed of two alpha catalytic subunits a nd two beta regulatory subunits. A C-terminal truncated form of the beta su bunit has been overproduced in Escherichia coli and purified to homogeneity . Two crystal forms of the truncated protein which diffract to at least 2 A ngstrom resolution have been obtained. Form I belongs to the monoclinic spa ce group P2(1), with unit-cell parameters a = 49.9, b = 92.9, c = 53.7 Angs trom, beta = 96.3 degrees, and yields plate-like crystals. Form II belongs to the tetragonal space group P4(2)2(1)2, with unit-cell parameters a = 132 .19, b = 132.19, c = 63.79 Angstrom, and produces rod-shaped crystals. Both crystal forms have a functional dimer in the crystal asymmetric unit.