Fig. 4

BACE1 controls neuronal cell surface levels of SEZ6 and SEZ6L. Primary, murine neurons were treated with the BACE inhibitor C3 or DMSO as a control. Proteins at the surface were labeled with biotin and enriched using streptavidin pull-down. Biotinylated SEZ6 and SEZ6L were detected by immunoblot. As a control, both proteins were also detected in whole cell lysates. Note, that only the mature 170 kDa form of SEZ6 was biotinylated at the cell surface. As a control, the ADAM10 substrate LDL receptor (LDLR) did not show a change in surface levels upon C3-treatment. As a further control, the cytosolic protein actin was only detected in whole lysates, but not among the surface biotinylated proteins