Figure 5.

Early endosome inactivation has no effect on the secretory pathway. Laz-B29 (A) or B4.14 (B) cells pulsed for 20 min with [³⁵S]methionine were processed (cross-link) or not (control) for early endosome inactivation and chased at 37°C for the indicated times. (A) TfR was immunoprecipitated and treated or not treated with endo H before analysis on SDS-PAGE. (B) After each chase period, the cell surface was biotinylated, and MHC class I molecules were immunoprecipitated. Cell surface MHC class I molecules were isolated using streptavidin–agarose. Samples were then boiled and analyzed on SDS-PAGE. Early endosome cross-linking has no effect on ER to Golgi to plasma membrane transport.