Fig. 4.

Silencing of ERAP1 alters amino acid usage at positions 1 and 2 of HLA-B*51-bound peptides, increasing the proportion of non-Pro Ala 2 residues at position 2. The percentage of HLA-B*51-bound peptides were assessed according to the abundance of amino acids at position 2 (A) and position 1 (B). The residues that were less abundant in ERAP1-silenced cells were labeled using down arrow. Two independent experiments were carried out. Chi-squared test with Bonferroni correction used for statistics. Dashed box highlights leucine. Broken horizontal lines indicate 5% of total peptides in each group.