Peptide antigen production by the proteasome: Complexity provides efficiency

Proteasomes have recently been shown to be central to the production of antigenic peptides that can bind to major histocompatibility complex class I molecules. Here, Marcus Groettrup and colleagues discuss the structural architecture of the proteasome and its proteolytic mechanisms with respect to the generation of antigenic peptides. They suggest that exchanges of proteolytic proteasome subunits and proteasome activators cooperate to optimize the production of antigens for cytotoxic T cells.