Interleukin-13 receptor alpha 2 (IL-133R alpha 2) binds IL- 13 with high affinity and plays an important role in IL-13 signaling as a decoy receptor. We expressed the extracellular domain of human IL-13R alpha 2 (1-313) in methylotrophic yeast Pichia pastoris. SDS-PAGE analysis by PAS staining and Western blot analysis detected the product of the extracellular domain of human IL-13R alpha 2 as glycoprotein from P. pastoris. The yield of purified extracellular domain of human IL-13Ra2 was 2 mg from I L of culture. From CD analysis, the 2D structure of the purified IL-13Ra2 showed the typical P-sheet. ELISA of the purified IL-13Ra2 detected the binding activity for human IL-13. Thus, it was found that the active extracellular domain of human IL-13Ra2 was expressed from P. pastoris. (c) 2007 Elsevier Inc. All rights reserved.