Relative affinities of IL-21 variants to IL-21Rα determined in ALPHAscreen competition test
Increasing concentrations of IL-21 variants were added to compete the binding of biotinylated wt IL-21 to IL-21Rα-His6. The relative affinities of IL-21 variants to IL-21Rα is expressed by the IC50mut/wt value. Values of IC50mut/wt greater than one indicate decreased binding affinity by the variants toward IL-21Rα relative to wt IL-21. IC50 values were measured in three independent experiments. mut, IL-21 variants.