Peptides decreased by treatment of cells with proteasome inhibitors.

Abbreviations: P1, amino acid residue in the P1 position of the cleavage site used to generate the N-terminus of the peptide; P1′, amino acid residue in the P1′ position of the cleavage site used to generate the C-terminus of the peptide; *, end of protein; *m, initiation methionine; Theor Mass, theoretical mass of the peptide; Ac-, acetyl. The amino acid sequence uses the standard single letter code and is indicated in upper case for the sequence of the peptide that was identified, and lower case for the peptide’s flanking sequences in the precursor protein.