Figure 3
Biotinylation efficiency of secretory and membrane bound t-IgE. (A) Western blot gel retardation assay of supernatants (t-sIgE) or cell extracts (t-mLIgE) from transiently transfected cells expressing secretory or membrane bound t-IgE. Where indicated, cell cultures were supplemented with biotin for 24 h and supernatants (dialyzed) or cell extracts reacted with streptavidin. (B) Flow cytometry and immunofluorescence microscopy assay on RBL-SX38 cells expressing human FcεRI incubated with biotinylated (red) or non-biotinylated (violet) t-sIgE; mAb 9E1 was detected with FITC-conjugated anti-mouse IgG antibody. (C) Flow cytometry and immunofluorescence microscopy assay of t-mLIgE displayed on transiently transfected HEK293T/17 cells, cultured in the presence (red) or absence (green) of biotin.