Figure 3: RAB6 vesicles fuse with melanosomes and deliver secretory cargo into melanosomes.
From: Routing of the RAB6 secretory pathway towards the lysosome related organelle of melanocytes
(a) Live imaging frame of MNT-1 cells expressing GFP-RAB6 and mCh-VAMP7 and corresponding time projection of RAB6-positive vesicles tracks (right) (see Supplementary Movie 4). (b) Consecutive time-lapse images of GFP-RAB6 vesicles (arrows) approaching and docking to GFP-RAB6 and mCh-VAMP7 positive melanosomes (arrowheads, and Supplementary Movie 5). (c–e) Electron micrographs of ultrathin cryosections of NPY-Venus expressing MNT-1 cells showed NPY association (PAG-10 nm, arrows) to Golgi apparatus (GA) and derived vesicles (c), as well as vesicles nearby melanosomes (d) and also in the lumen of melanosomes (e). (f) Live imaging frame of MNT-1 cells expressing NPY-Venus and mCh-VAMP7. (g) Linescan intensity profiles of NPY across VAMP7-positive melanosomes measured along white lanes highlighted by the 5X area in f. (h) Consecutive time-lapse images of the insets (in f) showing the partial delivery of NPY cargoes from the vesicle to the lumen of the melanosome (arrows and Supplementary Movie 6). (i) The NPY-Venus fluorescent intensity within mCh-VAMP7 melanosomes (in h) was measured over time and normalized to the mCherry intensity. Scale bars, 5 μm (a,b,f); 100 nm (c–e).
