Low-density crystal packing of human protein kinase CK2 catalytic subunit in complex with resorufin or other ligands: a tool to study the unique hinge-region plasticity of the enzyme without packing bias

A low-resolution structure of the catalytic subunit CK2α of human protein kinase CK2 (formerly known as casein kinase 2) in complex with the ATP-competitive inhibitor resorufin is presented. An overview of all published human CK2α crystal packings serves as the basis for a discussion of the factors that determine whether the open or the closed hinge/helix αD conformation is adopted.