Exogenous antigen noetic Class I MHC compartments Peptides (的 II上 Golgi complex D Invarant chain Pcptidc Calreticulin BD RougH Peptides endoplasmic Proteasome 坚3 reticulam Invariant 画→ Calnexin chain Class I MHO Tapasin cHass u MHC Protein Nucleus Endogenous pathway Exogenous pathway (class I MHC) <cl:ss II MHC)