Fig. 1.

Proteasome digestion of the insulin B chain. In vitro proteasome-mediated digestions of the 30-mer insulin B chain peptide containing potential HLA-A*0201–restricted epitopes. 20S proteasomes isolated from an Epstein–Barr virus-transformed B cell line (immuno proteasome) and an HeLa cell line (constitutive proteasome) were coincubated with 30-mer insulin B chain peptides at 37°C for 20 h. Digestion mixtures were analyzed by MS as described in Materials and Methods. The intensity is expressed as the percentage of total summed mass-peak intensities of digested 30-mer. Predicted epitope used for CTL induction is in bold.