Figure 1.

Biosynthesis and processing of proEGF forms in polarized MDCK cells. (A) MDCK cells expressing proEGF were grown on Transwell filters and metabolically labeled with ³⁵S-Translabel for 20 min. The label was then chased for different periods of time. Total cell lysates were prepared and immunoprecipitated with mAb-EGF. (B and C) Pulse–chase experiments and immunoprecipitations were performed as described above. Immunoprecipitates were washed with the appropriate buffers, divided into equal parts, and digested with either N-glycosidase F (B) or endo H (C) as described in Materials and Methods.