Crystallization and preliminary X-ray analysis of human grancalcin, a novel cytosolic Ca2+-binding protein present in leukocytes.

Recombinant human grancalcin, a calcium-binding protein from leukocytes, has been crystallized in the presence or absence of Ca(2+) by the vapor-diffusion method. Two crystal forms of apo grancalcin were obtained: space group P2(1), with unit-cell parameters a = 48.4, b = 81.1, c = 46.6 A, beta = 111.3 degrees, diffracting to 1.9 A, and space group C2, with unit-cell parameters a = 97.0, b = 51.9, c = 75.9 A, beta = 108.5 degrees, diffracting to 2.4 A. Crystals were also grown in the presence of 5 mM Ca(2+). They also belong to space group C2, with unit-cell parameters a = 97.4, b = 50.3, c = 77.6 A, beta = 108.2 degrees, which are very similar to the second apo grancalcin form. These crystals diffract to 2.5 A.