||Proteasomes generate peptides that are presented by major histocompatibility complex (MHC) I molecules to other cells of the immune system. Proteolysis is conducted by 20S proteasomes, complexes of 28 subunits arranged as a cylinder in 4 heteroheptameric rings: alpha-1 to -7, beta-1 to -7, beta-1 to -7, and alpha-1 to -7. The catalytic subunits are beta-1, beta-2), and beta-5 (PSMB5; MIM 600306). Three additional subunits, beta-1i, beta-2i, and beta-5i, are induced by gamma-interferon and are preferentially incorporated into proteasomes to make immunoproteasomes. PSMB11, or beta-5t, is a catalytic subunit expressed exclusively in cortical thymic epithelial cells .