Figure 3.

Intracellular transport and stability of MHC I molecules. (A) HeLa cells stably transfected with pCEP4-K3 (Lower) or the pCEP4 vector alone (Upper) were metabolically labeled for 20 min and chased for the indicated time periods. After being lysed in 1% Nonidet P-40, lysates were divided into three aliquots. Two were kept on ice and one was incubated at 37°C for 1 h. Heterodimeric MHC I molecules were immunoprecipitated with mAb W6/32 and treated with endo H where indicated. (B) BJAB cells stably transfected with pcdef3-K5 or the vector alone were radiolabeled for 30 min and chased for the indicated time periods. MHC I molecules in cell lysates were immunoprecipitated with mAb W6/32. Quantitation of the data is presented as a fraction of initial MHC I levels; ⋄, K5 expressing cells; ●, control cells. (C) BJAB cells stably transfected with pcdef3-K5 were radiolabeled for 30 min and chased for 3 h in the presence or absence of the indicated inhibitors. MHC I molecules were immunoprecipitated by using mAb W6/32.