Recycling MHC class I molecules and endosomal peptide loading

AUTOR(ES)

Grommé, Monique

FONTE

The National Academy of Sciences

RESUMO

MHC class I molecules usually present peptides derived from endogenous antigens that are bound in the endoplasmic reticulum. Loading of exogenous antigens on class I molecules, e.g., in cross-priming, sometimes occurs, but the intracellular location where interaction between the antigenic fragment and class I takes place is unclear. Here we show that measles virus F protein can be presented by class I in transporters associated with antigen processing-independent, NH4Cl-sensitive manner, suggesting that class I molecules are able to interact and bind antigen in acidic compartments, like class II molecules. Studies on intracellular transport of green fluorescent protein-tagged class I molecules in living cells confirmed that a small fraction of class I molecules indeed enters classical MHC class II compartments (MIICs) and is transported in MIICs back to the plasma membrane. Fractionation studies show that class I complexes in MIICs contain peptides. The pH in MIIC (around 5.0) is such that efficient peptide exchange can occur. We thus present evidence for a pathway for class I loading that is shared with class II molecules.

Documentos Relacionados

• Mouse B lymphocyte specific endocytosis and recycling of MHC class II molecules.
• Early endosomal maturation of MHC class II molecules independently of cysteine proteases and H-2DM
• Stability of empty and peptide-loaded class II major histocompatibility complex molecules at neutral and endosomal pH: Comparison to class I proteins
• Positive selection of an MHC class-I restricted TCR in the absence of classical MHC class I molecules
• Tapasin enhances MHC class I peptide presentation according to peptide half-life