Klaus Früh, Ph.D.

Fig. 1: Antigen-derived peptides are usually generated in the cytosol by the ubiquitin proteasome complex and are translocated into the endoplasmic reticulum (ER) by the peptide transporters TAP. Peptide generation by proteasomes is a by-product of general protein turnover in cells that takes place in every eukaryotic cell. From the pool of peptides produced by the proteasome, TAP selects the peptides within the size range optimal for MHC binding and translocates them into the lumen of the ER. In the ER, the MHC-specific chaperone tapasin retains empty MHC class I molecules until they acquire peptides. Moreover, tapasin also mediates their interaction with TAP. Once assembly with peptides is completed, MHC class I molecules travel to the cell surface.

Return to Immune Evasion text