Fig. 1.

PEIVIYQYM (PM9) is a new HIV-1–derived peptide binding HLA-E. (A) RMA-S cells stably expressing HLA-E*01:01, HLA-E*01:03 or HLA-B*18:01 were pulsed with increasing concentration of either PM9 or VL9 peptides and the cell-surface stabilization of the HLA-E and HLA-B molecules were determined by using mAbs 3D12 and W6/32, respectively. Please see gating strategy in Fig. S2. (B) A single chain peptide-β₂-microglobuline-MHC-E heavy chain trimer (left) cell-surface stabilization was used to test candidate peptides for binding to MHC-E. Briefly, DNA fragments coding for the tested peptides were inserted into a plasmid for expression of the entire trimer in one open-reading frame. This plasmid DNA was transiently transfected into HEK 293T cells and the trimer surface expression (red line) was detected by antibodies indicated below the graphs using flow cytometry. Stabilization by VL9 (yellow area) and irrelevant (pink area) peptide were used as positive and negative controls. Please see gating strategy in Fig. S3.