Cryo-ET of individual PM and SV vesicles. (A and B) Gray scale tomographic slice views of individual PM and SV vesicles that were separately frozen on EM grids, respectively. SV vesicles include reconstituted Syt1 and synaptobrevin-2 whereas PM vesicles include syntaxin-1A and SNAP-25A. (C) Representative subtomograms (tilt axes along the solid white lines) of SV (light gray, Top) and PM vesicles (dark gray, Bottom). Protruding densities (arrows) from both vesicles are seen both in 2D-slice (Left) and 3D isosurface views (Middle and Right). These densities likely correspond to Syt1 in SV vesicles and syntaxin-1A/SNAP-25A complexes in PM vesicles. Tomogram 2D slice thickness: 1 pixel = 3.42 Å. (Scale bars: black, 100 nm; gray, 25 nm.) Thin white lines, tilt axes.