Specificity of the proteasome and the TAP transporter

The generation of antigenic peptides and their transport across the membrane of the endoplasmic reticulum for assembly with MHC class I molecules are essential steps in antigen presentation to cytotoxic T lymphocytes. Recent studies have characterized the substrate specificities of the proteasome and the transporter associated with antigen processing. It is interesting to compare the specificity of this transporter to the wide spectrum of peptides generated by the proteasome, to the binding motifs of MHC class I molecules and in particular to the principles of T cell recognition.