Proteasome subtypes and the processing of tumor antigens: increasing antigenic diversity

► Peptide splicing by the proteasome produces diverse MHC-I binding peptides. ► Two proteasome subtypes that are intermediate between standard and immunoproteasome. ► Cytosolic metallopeptidases produce antigenic peptides presented by MHC class I. ► Insulin-degrading enzyme, nardilysin and thimet oligopeptidase. ► Increased diversity of the antigenic peptide repertoire.