H. Ziegler et al., The luminal part of the murine cytomegalovirus glycoprotein gp40 catalyzesthe retention of MHC class I molecules, EMBO J, 19(5), 2000, pp. 870-881
Murine cytomegalovirus (MCMV) interferes with the MHC class I pathway of an
tigen presentation. The type I transmembrane glycoprotein gp40, encoded by
the gene m152, retains major histocompatibility complex (MHC) class I compl
exes in the endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGI
C)/cis-Golgi. These MHC class I complexes are stable, show an extended half
-life and do not exchange Pz-microglobulin, whereas gp40 reaches an endosom
al/ lysosomal compartment where it subsequently is degraded. The analysis o
f regions within the viral protein that are essential for MHC class I reten
tion revealed that a secreted form of gp40, lacking the cytoplasmic tail an
d the transmembrane region, still has the capacity to retain MHC class I co
mplexes, Continuous expression of gp40 is not required for MHC class I rete
ntion, Our data indicate that the retention of MHC class I complexes in the
ERGIC/ cis-Golgi is triggered by gp40 and does not require the further pre
sence of the viral protein.