Purification of recombinant proteins. Recombinant MC53L, MC54L, huIL-18BP, and muIL-18BP were purified by metal affinity chromatography, were analyzed by SDS/PAGE, and were detected by Coomassie blue staining (Left) or by chemiluminescence after Western blotting with a mAb to the polyhistidine tag (Right). Hu, huIL-18BP; Mu, muIL-18BP; 53, MC53L; 54, MC54L. The positions and masses in kilodaltons of protein markers are shown on the extreme left.