Purification, crystallization and preliminary X-ray diffraction analysis of the IL-20-IL-20R1-IL-20R2 complex

Interleukin-20 (IL-20) is an IL-10-family cytokine that regulates innate and adaptive immunity in skin and other tissues. In addition to protecting the host from various external pathogens, dysregulated IL-20 signaling has been shown to contribute to the pathogenesis of human psoriasis. IL-20 signals through two cell-surface receptor heterodimers, IL-20R1-IL-20R2 and IL-22R1-IL-20R2. In this report, crystals of the IL-20-IL-20R1-IL-20R2 ternary complex have been grown from polyethylene glycol solutions. The crystals belonged to space group P4₁2₁2 or P4₃2₁2, with unit-cell parameters a = 111, c = 135 Å, and diffracted X-­rays to 3 Å resolution. The crystallographic asymmetric unit contains one IL-­20-IL-20R1-IL-20R2 complex, corresponding to a solvent content of approximately 54%.