Crystallization and preliminary X-ray diffraction analysis of the ternary human GM-CSF receptor complex

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a haemopoietic growth factor that acts though a ternary receptor signalling complex containing specific α (GMRα) and common β (βc) receptor subunits. Human GM-CSF is encoded by the gene csf2, while the genes for GMRα and βc are csf2ra and csf2rb, respectively. Crystals of the ternary ectodomain complex comprising GM-CSF and the soluble extracellular regions of both the GMRα subunit and either βc or its glutamine-substitution mutant N346Q were obtained using the hanging-drop vapour-diffusion method. The best diffracting crystals of the ternary complex were obtained using the N346Q mutation of the βc subunit. These crystals grew using polyethylene glycol 3350 with a high concentration of proline, belonged to space group P6₃22 and diffracted to 3.3 Å resolution.