Fig. 3.

IL3Rα site 1b residues are a functional hotspot in mediating IL-3 signalling. Functional activity of IL3Rα mutants was measured in a wild-type IL-3 or b IL-3 K116W dose–response proliferation assays using CTLL-2 cell lines transduced to co-express the βc subunit with either wild-type or mutant forms of IL3Rα. The identity of each IL3Rα mutant is shown along with the substituted residue (m). Half-maximal responses (ED₅₀) were calculated from each experiment and averaged. The dashed line represents the response from cells expressing wild-type IL3Rα. Errors represent SEM. Statistical significance of differences in functional response between wild-type IL3Rα and the mutant forms of IL3Rα (p) was determined using a two-tailed unpaired t test and are shown as black asterisks above the data for each mutant. Statistical significance of differences in functional response between wild-type IL-3 and IL-3 K116W (p) was also determined using a two-tailed unpaired t test and are shown as blue asterisks between data sets a and b. ns p > 0.05, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001