The molecular mechanism responsible for capturing, sorting and retrieving vesicle membraneproteins following triggered exocytosis is not understood. Here we image the post-fusionrelease and then capture of a vesicle membrane protein, the vesicular acetylcholine transporter, from single vesicles in living neuroendocrine cells. We combine these measurementswith super-resolution interferometric photo-activation localization microscopy and electronmicroscopy, and modelling to map the nanometer-scale topography and architecture of thestructures responsible for the transporter’s capture following exocytosis. We show that afterexocytosis, the transporter rapidly diffuses into the plasma membrane, but most travels onlya short distance before it is locally captured over a dense network of membrane-residentclathrin-coated structures. We propose that the extreme density of these structures acts as ashort-range diffusion trap. They quickly sequester diffusing vesicle material and limit itsspread across the membrane. This system could provide a means for clathrin-mediatedendocytosis to quickly recycle vesicle proteins in highly excitable cells.
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