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. Author manuscript; available in PMC: 2012 Oct 26.
Published in final edited form as: Nature. 2012 Mar 25;484(7395):529–533. doi: 10.1038/nature10975

Figure 1. In vitro evolution of human IL-2 variants with high affinity for IL-2Rβ.

Figure 1

a, IL-2 displayed on yeast recapitulates cooperative receptor-binding activity. As measured by flow cytometry, IL-2 binds weakly to IL-2Rβ (left panel), undetectably to γc (middle panel), and cooperatively forms the IL-2Rβ/γc heterodimer (right panel). b, Enrichment of IL-2 variants on yeast by selection with progressively lower concentrations of IL-2Rβ. Arrows indicate an emerging population of high affinity IL-2Rβ binders (see also Supplementary Fig. 2). c, Sequences and affinities for IL-2Rβ of selected mutants from the first (mutant 6-6) and second (mutants D10 and H9) generation libraries (see Supplementary Fig. 3 for an extended table). d, On-yeast stimulation of YT-1 cells (human NK cell line) by wild-type (WT) IL-2-yeast and high affinity variants (super-2s) (see also Supplementary Fig. 4).