Figure 1.

Schematic representation depicting processing of antigens presented by class I MHC molecules. 1) Intracellular proteins are proteolytically degraded within proteasomes. 2) Proteolytic degradation of intracellular proteins yields antigenic peptides of nine to eleven amino acids. 3) Antigenic peptides generated by the proteasomes are transported into the endoplasmic reticulum. 4) Newly synthesized class I MHC molecules bind antigenic peptides within in the endoplasmic reticulum. 5) Class I MHC-antigenic peptide complexes are exported through the Golgi and to the cell surface, for presentation of antigenic peptide to CD8⁺ T cells.