Figure 4.

PC7 EXEXXXL motif is critical in multiple cell lines. A, Western blot analysis of cell lysates (cells) and media (med) after overexpression of hTfR1-V5, empty vector, hPC7, L720A, E721A/S722A/V723A (ESV₇₂₃-AAA), S722A, and V723A mutants in HEK293 cells. Normalization was performed using the hTfR1-V5 shed by hPC7 as a reference. These results are representative of three independent experiments. B and C, Western blot analysis of cell lysates (cells) and media (med) after overexpression of hTfR1-V5, empty vector, hPC7, its truncated form without the CT (ΔCT), and different CT mutants in HeLa cells (B) or in HuH7 cells (C). Normalization was performed using the hTfR1-V5 shed by hPC7 as a reference. The main mutants composing the EXEXXXL motif are annotated by a star. These results are representative of three independent experiments. All error bars indicate averaged values ± S.D. *, p < 0.1; **, p < 0.01; ***, p < 0.001; ns, not significant (Student's t test).