Antigen processing for presentation by MHC class I molecules.

The association of peptide fragments with MHC class I molecules is believed to be a requirement for the assembly of the MHC class I molecules in the endoplasmic reticulum, and transportation of the MHC molecules from the endoplasmic reticulum to the cell surface. Recently, investigators have begun to elucidate the mechanisms of fragmentation and transport of peptide fragments within antigen-presenting cells, and to define size and structure of naturally processed peptides bound to MHC complexes.