Analysis of Major Histocompatibility Complex Class I Interactions with Endoplasmic Reticulum Proteins

Major histocompatibility complex class I (MHC-I) molecules alert cytotoxic T-lymphocytes to the presence of intracellular pathogens and tumors by presenting short peptides derived from pathogen- or tumor-specific proteins. To present a peptide, an MHC-I heavy chain (HC) binds the peptide and a small accessory protein called β₂ -microglobulin (β₂ m) in the endoplasmic reticulum (ER), and then migrates to the cell surface. The outer domains of the MHC-I HC and the antigenic peptide are then available to bind to T cell receptors.