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. 2003 Oct;110(2):163–169. doi: 10.1046/j.1365-2567.2003.01738.x

Figure 2.

Figure 2

Viral inhibition of the MHC class I antigen presentation pathway. Viruses have evolved proteins that inhibit the MHC class I pathway at virtually every step. US2 and US11 dislocate the MHC class I heavy chain into the cytosol where it is degraded by the proteasome. ICP47 and US6 inhibit peptide translocation by TAP. E19 inhibits MHC class I association with TAP, E19 also inhibits MHC class I trafficking by retrieving MHC class I molecules from the cis-Golgi. Similarly US3 and US10 inhibit the ER export of class I molecules. U21 diverts MHC class I molecules to the lysosome. Nef down-regulates MHC class I molecules from the plasma membrane sequestering them in the TGN. Finally K3 and K5 down-regulate MHC class I molecules and sort them into the late endocytic pathway where they are degraded.