Fig. 1

Mitochondrial fission 1 protein (Fis1) and syntaxin 17 (STX17) interact and partially colocalize. a, b HeLa cells were transfected with Flag-tagged vector or Fis1. After 24 h, cells were collected for immunoprecipitation (IP) with anti-Flag beads. Coomassie blue staining was used to visualize bands 1 and 2 (a). Results for mass spectrometry analysis of band 1 and 2 are summarized (b). c Cells treated as in a were extracted. Anti-Flag immunoprecipitates were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotted for STX17 and Flag. Asterisk indicates a non-specific band. d HEK293T cells were co-transfected with Myc-tagged STX17 and Flag-tagged plasmids as indicated. Cells were solubilized for IP with anti-Flag and analyzed with Myc and Flag antibodies respectively. e HeLa cells were transfected with green fluorescent protein (GFP)-tagged vector or STX17 (green) and mCherry-tagged vector or plasmid encoding Fis1 (red) for 24 h. Cells were fixed and stained with anti-Tom20 (cyan). Hoechst, blue. Scale bar, 10 µm. f HeLa cells were treated with the indicated small interfering RNA (siRNA) for 24 h before transfecting with GFP-tagged Fis1 (green) or GFP-STX17 (green) for further 24 h. Representative confocal images of live cells are shown. Mitochondrial morphology was visualized using MitoTracker Red (MTR, red). Scale bar, 10 µm. White arrowhead indicates cells with decreased MTR. g Quantification of cells with decreased MTR as shown in f. Error bars, SD. ***P < 0.001 (two-tailed unpaired Student’s t test, n = 150 cells from three independent experiments). h STX17 and Fis1 silencing was verified in HeLa cells by immunoblotting