Fig. 3.

Yeast codisplay and surface detection of FLU peptide and FLU-bound soluble HLA-DR1. (A) The yeast parent strain or yeast expressing HLA-DR1, Aga2p-FLU, or both were double-labeled with anti-HA and anti-DR1 antibodies and analyzed by flow cytometry. (B) The yeast parent strain and yeast expressing Aga2p-P1-Ala alone or with HLA-DR1 or yeast expressing Aga2p-FLU with or without coexpressed HLA-DR1 treated with DTT or Factor Xa protease, as indicated, were double-labeled and analyzed by flow cytometry. (C) Yeast expressing Aga2p-FLU were cocultured at 1∶1 ratio with yeast expressing soluble HLA-DR1 or cultured in medium preconditioned by growing codisplaying yeast prior to labeling and analysis.