Figure 8. Bim CTS binds with non-transmembrane topology to cellular membranes.

(A) Selected images for sub-cellular localization of ^VBimEL and BimEL^V in BMK-DKO cells compared to MitoTracker. The scale bar represents 10 µm. (B) In live cells ^CBcl-XL binding to BimEL^V is resistant to ABT-263. FLIM-FRET binding curves for the interactions between ^CBcl-XL and BimEL^V in ABT-263 (blue) or DMSO (green) treated BMK-DKO cells expressing ^CBcl-XL. Binding of ^CBcl-XL to ^VBimEL (black) measured in the same three experiments is shown for comparison. Data from ROIs from three independent experiments were combined and used to generate binding curves with 95% confidence intervals as in Figures 1 and 2. (C) Sub-cellular localization of BimEL^V is impaired compared to ^VBimEL but ABT-263 resistant binding to ^CBcl-XL (R_ABT-263) is unchanged. Colocalization for Venus and MitoTracker-Red was measured in this experiment for manually selected regions of interest from transiently transfected cells expressing ^VBimEL or BimEL^V (Pearson’s r, red); Error bars, SEM, n > 30 cells. R_ABT-263 of ^CBcl-XL:^VBimEL or ^CBcl-XL:BimEL^V complexes, black dots. Data are mean ±95% confidence intervals calculated from FLIM-FRET binding curves shown in panel b.