Membrane compartments—endocytic sites, clathrin-coated vesicles, and ER compartments. (A and B) Single slices of two IsoNet-processed tomograms are shown on the left. Both tomograms show an endocytic site, highlighted by blue (A) and purple (B) squares, respectively. For both tomograms, these sites are shown at higher magnification and different z-positions to better illustrate the structural details. Endocytosis-associated proteins, potentially BAR-domain proteins, can be seen assembled at the neck of the forming vesicle, indicated by blue and purple arrowheads. The difference in z-position is indicated above each image. (C) A single central slice of an IsoNet-processed tomogram shows a clathrin-coated vesicle annotated by a yellow arrowhead. (D) Four exemplary regions containing ER compartments (annotated by white arrowheads) in IsoNet-processed tomograms are shown. All tomogram slices have a thickness of 1.71 nm. Scale bar dimensions are annotated in the figure.