Figure 2.

Influence of ERAP1 polymorphism on the HLA-B*27 peptidome. (A) Effects of K528R. Comparison of the B*27:05 ligands over-represented (>1-fold) in a cell line (LG2, N: 2215 peptides) expressing the Hap3 variant of ERAP1 (red), with those over-represented in a cell line (C1R05, N: 2801) expressing the Hap8 variant (green). Hap3 and Hap8 differ by R127P, I276M, and K528R, but the two former changes have much less influence on peptide trimming. The comparisons involve peptide length (upper panel), joint frequencies of P1 residues with low or intermediate+high susceptibility to ERAP1 among 9-mers (second panel) or longer peptides (third panel), and theoretical affinity of the total ligands, with the medians indicated by bars. (B) Effects of E730Q. Comparison of the B*27:05 ligands over-represented (>1-fold) in the LG2 cell line (Hap3: red), with those over-represented in LCL 6370 (blue) expressing the Hap2 variant (N: 2,444 and 2,869 peptides, respectively). Hap3 and Hap2 differ only by the E730Q change. Conventions are as in (A). The statistical significance of the changes is indicated by the p-values, as estimated by the χ² (three upper panels) or Mann–Whitney tests (lower panels). These data were originally published in reference (102).