Screening for improved DR3 mutants using yeast surface display.

(A) Yeast surface display of DR3; DR3 (turquoise) is displayed as an Aga2 (gray) fusion on the surface of the yeast. Expression and TL1A binding are detected by fluorescent antibodies (green) and streptavidin (yellow), respectively. (B) Flow cytometry histogram analysis of cell populations displaying native DR3 (blue), and DR3 mutant libraries after two rounds (R2, red) and three rounds of enrichment (R3, green) for TL1A binding. In each round of enrichment, tje cell population exhibiting high expression (FITC signal) and TL1A binding (APC signal) were sorted according to the fluorescent signals. A cell population that was not surface displayed is shown in black. Analysis of cells was performed following incubation with 0.2 μM TL1A.