¹²⁵I–IL-13 binding to CHO-K1 and T98G cells transfected with the IL-13Rα2, IL-13Rα1, IL-4Rα, and γ_c chains.

cDNA for various receptor chains (6 μg/chain) was transfected into cells (1 × 10⁶) by using GenePORTER reagent for 48 hours. For the IL-13 binding assay, 1 × 10⁶ transfected cells were incubated with 200 pmol/L of ¹²⁵I–IL-13 with or without a 200-fold molar excess of unlabeled IL-13 (A) or control CHO-K1 and IL-13Rα2–transfected cells with IL-13 or IL-4 (B). Binding assays were performed in 2 separate experiments. Cell bound radioactivity was determined as described in “Materials and methods.”