Fig. 6. Krm increases cell-surface levels of LRP6. (A) Western blot analysis of HEK293T cells transfected with flag-LRP6 and the indicated constructs. Samples were treated with EndoH as indicated. Arrows indicate the EndoH-resistant mature and EndoH-sensitive immature forms of LRP6. (B) Cell surface biotinylation assay. HEK293T cells were co-transfected with flag-LRP6 and the indicated constructs. After cell surface biotinylation, cell lysates were immunoprecipitated with anti-flag antibody and subjected to SDS-PAGE and western blot analysis. Membranes were probed with streptavidin-HRP to detect plasma membrane LRP6 (upper panel) and anti-flag antibody to detect total LRP6 (lower panel). (B') The cytoplasmic protein NME1 is not biotinylated (upper panel). Lower panel: Total NME1 protein. dg, deglycosylated form; im, EndoH-sensitive immature form; ma, EndoH-resistant mature form.