Figure 2. Subtomogram averaging reveals the multipartite nature of the neck complex.
(A) Central slice through the unsymmetrized subtomogram average of the neck complex, low-pass filtered to its Gold-standard resolution 34 Å. Arrows indicate densities that are referred to as the ‘base’ and the ‘crown.’ The crown is located on the cytoplasmic side and is composed of three rings. Density is black. Scale bar, 100 Å. (B) 3D segmentation of the unsymmetrized subtomogram average shown in (A). The spherule membrane (yellow) is radially symmetrized for clarity. Dark blue: base, red: putative RNA, cyan: crown, and light blue: teeth. (C and D) Two views of the neck complex related by the indicated rotation. (E) Color key for all panels. (F) Cross-section through the subtomogram average of the neck complex with C12 symmetry imposed, low-pass filtered to its Gold-standard resolution 28 Å. (G) Surface view corresponding to (F). (H) The structure of the isolated nsP1 (from Jones et al., 2021) low-pass filtered to the resolution of our average. (I) Superimposition of nsP1 onto the base of the protein neck complex. (J) Slice through the unsymmetrized subtomogram average, as in (A), with a slice of the fitted nsP1 superimposed on the base of the complex.
Figure 2—figure supplement 1. Subtomogram averaging of the neck complex.
