Fig. 1
Screening for transmembrane RING domain E3 ligases regulating GABAB receptor cell surface expression. HEK-293 cells were transfected with plasmids for GABAB1, GABAB2 and EGFP as a control (Ctrl) or with GABAB1, GABAB2 and the indicated E3 ligases. After 2 days, the cells were tested for cell surface expression of GABAB1 (a) and GABAB2 (b) by immunofluorescence staining using antibodies directed against GABAB1 and GABAB2. (a) Co-expression of MARCH1 downregulated the cell surface expression of GABAB1.Top: representative images (scale bar: 10 μm). Bottom: quantification of fluorescence intensities (mean ± SD of 85–90 cells per condition, 4 independent experiments). (b) Co-expression of MARCH1 downregulated the cell surface expression of GABAB2. Top: representative images (scale bar: 10 μm). Bottom: quantification of fluorescence intensities (mean ± SD of 80–132 cells per condition, 4 independent experiments). Brown-Forsythe and Welch’s one-way ANOVA followed by Games-Howell’s multiple comparisons test (****, p < 0.0001).
