A complex between interleukin-10 and the extracellular domain of its high-affinity receptor (sIL-10R1) has been crystallized from polyethylene glycol solutions. Crystals suitable for diffraction analysis required the modification of the NXS/T glycosylation sites on sIL-10R1 by site-directed mutagenesis and inclusion of the detergent cyclohexyl-methyl-beta-D-maltopyranoside in the crystallization experiments. The crystals belong to space group P3(2)12 or its enantimorph P3(1)12, with unit-cell parameters a = b = 46.23, c = 307.78 A, alpha = beta = 90, gamma = 120 degrees, and diffract X-rays to approximately 2.9 A. The IL-10 dimer is positioned on a crystallographic twofold, resulting in one IL-10 chain and one sIL-10R1 chain in the asymmetric unit, which corresponds to a solvent content of approximately 44%.
