FIGURE 3.

Expression of recombinant pro-IL-33 and spIL-33. Recombinant spIL-33 was expressed in E. coli. A, molecular size of recombinant spIL-33 was ∼5 kDa smaller than that of pro-IL-33. B, recombinant spIL-33 was first purified by a TALON metal affinity chromatography. The purified protein was visualized by 10% SDS-PAGE and Coomassie Brilliant Blue staining. The purified (35 kDa) recombinant spIL-33 protein was further purified by HPLC and visualized by silver staining (C) and Western blotting (D). The data represent one of four independent experiments.