Immunological functions of the proteasome. 
Proteasomes are highly abundant cytosolic and nuclear protease complexes that degrade most intracellular proteins in higher eukaryotes and appear to play a major role in the cytosolic steps of MHC class I antigen processing.  This review summarizes the knowledge of the role of proteasomes in antigen processing and the impact of proteasomal proteolysis on T cell-mediated immunity.