The murine cytomegalovirus (MCMV) protein m4/gp34 is unique among known viral genes that target the major histocompatibility complex (MHC) class I pathway of antigen presentation in the following two ways: it is found in association with class I MHC molecules at the cell surface, and it inhibits antigen presentation without reducing cell surface class I levels. The current study was undertaken ...

(MHC) class I molecules are polymorphic cell surface glycoproteins that play an essential role in immune surveillance. In the MHC class I antigen presentation pathway, peptides derived from cytosolic proteasome-mediated proteolysis are transported into the endoplasmic reticulum (ER) via the transporter associated with antigen processing (TAP), reviewed in ref. 1. In the ER lumen, translocated p...