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TECPR2-positive peripheral early endosomes are accessible to endocytosed cargo and undergo membrane remodeling, including tubulation and fission events. A, B Live-cell imaging of HeLa cells co-expressing GFP-TECPR2 (green) and RFP-Rab5 (magenta) (see Supplementary Movie 3). The blue arrowheads indicate GFP-TECPR2- and RFP-Rab5-positive vesicles forming short tubules and undergoing fission to form two separate endosomes. The yellow arrowheads indicate GFP-TECPR2-positive tubules. Scale bars: 5 µm. B The line-scan analysis shows the fluorescence intensity of GFP-TECPR2 and RFP-Rab5 across the indicated endosome (marked by a blue arrowhead). C The graph displays the fluorescence intensities of GFP-TECPR2-positive vesicles during the fission and fusion processes. Linear regressions are shown for a total of 15 vesicles from three independent experiments. Slightly positive and negative slopes are marked in green and red, respectively, and the stationary events are indicated in gray. D Live-cell imaging of HeLa cells co-expressing GFP-TECPR2 (green) and untagged-Rab5 and incubated with Alexa 568-Tfn ligand (magenta) (see Supplementary Movie 6). The live-cell imaging was started after 5 min of Alexa 568-Tfn pulse. The white arrowheads indicate GFP-TECPR2 vesicles containing Alexa 568-Tfn, and one of the vesicles is undergoing elongation and eventually fission. The yellow arrowheads indicate Alexa 568-Tfn-containing GFP-TECPR2-positive tubules undergoing a fission event. Scale bars: 5 µm. Source data are provided as a Source Data file.
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