Fig. 3.

3D cryo-electron tomography of the caveolar coat complex reveals a two-layered coat architecture. (A) Gallery of equatorial tomographic slices of five representative particles. Edge lengths and dihedral angles are exemplified for one particle (right). (B) Average intensity projections of tomographic equatorial slices of two particles. Three-way junctions and polygonal profiles are highlighted. The image on the right shows superimposition of 10 three-way junctions. (C,E) Gallery of tomographic slices of two representative particles. Numbers indicate z-slice shown. Blue arrowheads depict discrete peripheral densities. The large black arrowhead in C indicates a gap in the protein coat, which is likely to correspond to the opening of the caveolar neck. (D) 3D surface rendering of the particle shown in C. Shown are a G2,1 polyhedral cage (left), the same cage superimposed onto the particle density (middle) and a close-up view (right). (F) 3D surface rendering of the particle shown in E. The central polyhedral cage and the peripheral filamentous coat are colored in white and blue, respectively. Arrowheads point to contacts between the central and peripheral coats. Shown are a top, end-on view (left), a side view (middle) and a sliced side view exposing the inner polyhedral cage (right). (G) Tomographic analysis of the pole of an 80S-CCC. An overlay with a G2,1 polyhedral cage is shown to illustrate the alignment of the peripheral densities (pseudo-colored in blue) along the edges of the inner polyhedral cage. (H) Tomographic analysis of the pole of an 80S-CCC. Blue arrowheads indicate filamentous densities with regular spacing. Scale bars: 20 nm unless stated otherwise. In B, C, E, G and H, a diagram of the slice(s) shown in the image is present at the top right.