Figure 5.
Bcl-xL localization and retrotranslocation is influenced by the C terminus. (a) Fluorescence loss in photobleaching (FLIP) measurements of wild-type (wt) green fluorescent protein (GFP)-Bcl-xL (top) or C-terminal deletion variants of Bcl-xL in the absence of Bax. Cytosolic GFP fluorescence of the targeted cells (circled) is reduced after 100 s and Bcl-xL is detected only on the mitochondria (arrows). Time points in seconds are displayed above the images. A scale of 10 μm is shown by the white bar in every image. (b) Retrotranslocation rates measured for wt Bcl-xL and C-terminal deletion variants of Bcl-xL in the absence (black) and presence of Bax (white) or in the presence of Bax and 1 μM ABT-737 (gray). Data represent averages±S.D. P-values according to a one-way analysis of variance (ANOVA) test are displayed. (c) FLIP measurements of mitochondrial wt GFP-Bcl-xL without (solid black line) and with overexpressed Bax (broken black line) and measurements for mitochondrial GFP-Bcl-xL Δ2 in the absence (solid dark gray line, full circle) and presence of overexpressed Bax (broken dark gray line, open circles) are displayed. Fluorescence of the neighboring cell is shown as control (light gray line). Data represent averages±S.E.M. from 20 region of interest (ROI) measurements per condition