Purification, crystallization and preliminary X-ray diffraction studies of a Ca²⁺-binding protein, human S100P

S100P, a Ca²⁺-binding protein, is a member of the S100 family. Its presence is associated with the development of prostate cancer, but its cellular function is not known. Recombinant human S100P has been expressed and purified in bacterial cells and crystals of human S100P in the calcium-bound state have been grown using the vapour-diffusion technique with PEG 4000 as precipitant. Diffraction data have been obtained to a resolution of 2.0 Å from a single frozen S100P crystal which belongs to the space group P4₁2₁2, with unit-cell parameters a = b = 60.8, c = 47.6 Å.