Fig. 3: MGS4_V8 traffics to and accumulates in lysosomes over time.

a H1299 cells were labelled with GFP-tagged organelle-specific proteins for ER, Golgi, lysosome, mitochondria, nucleus, plasma membrane, and cytosol (green). Cells were incubated with 50 nM MGS4_V8-Streptavidin Alexa Fluor 555 (red) for 1 h at 37 °C, then fixed and counterstained with DAPI (blue). MGS4_V8 colocalizes with lysosomes observed as yellow puncta indicated by the red arrows. No significant colocalization is observed with other subcellular organelles. b Lysosome labelled H1299 cells (green) were incubated with 50 nM MGS4_V8-Streptavidin Alexa Fluor 555 (red) for 0.5, 1, 4, or 24 h, then washed, fixed, and counterstained with DAPI (Blue). Representative single z-slice images are shown. Peptide-filled vesicles can be seen trafficking to lysosomes at 30 min, with many already colocalizing by 1 h. Most peptide is found within lysosomes by 4 h and retained there at 24 h. c Maximally projected, compressed z-stacks from images in panel b. The scale bar in all images represents 10 µm.