Figure 3.

Presence of tailless A2 inhibits dislocation of endogenous MHC class I heavy chains. Cells were pulse labeled for 5 min and chased for the times shown, all in the presence of ZL₃VS. The bracket with + and - denotes the forms of heavy chain with and without glycan, respectively. In US11-expressing cells (a), full length class I heavy chain is lost (a decrease in W6/32-reactive material) or dislocated (an increase in −CHO form). The tailless A2 continues to fold (increasing W6/32) while no deglycosylated tailless A2 accumulates. There is increased recovery of US11 in the cells expressing tailless A2. In control cells (b), endogenous and tailless heavy chains mature at similar rates. Fractionation of US11-expressing cells transfected with tailless A2 (c) shows the presence of deglycosylated full length heavy chains in the cytosol and no accumulation of tailless A2 in the cytosol.