Figure 2. Structure of the isolated yeast NPC.

(A) Composite 3D map of the inner ring and double outer rings viewed from the nuclear side: nuclear, double outer ring (gold), inner ring (IR, light blue).

B. The inner ring is shown with local 2-fold axes and membrane attachment complexes that contain Nup157 pairs, Pom152 and Pom34 (MAC157, black asterisks), and Nup170 pairs with Ndc1 (MAC170; blue asterisks).

(C) A cross-section of the inner ring with ɑ-helical rods throughout.

(D) A single spoke is segmented and viewed along the central 2-fold axis to reveal the three major layers.

(E) A central slice through the spoke with the orientation of Figure 2H shows the gap between inner and outer spoke domains (ISD and OSD, respectively). Cavities are marked with asterisks.

(F) A central section with three docked models for the spokes and double outer ring (oriented as in C). β-propellers in the Y-complexes are highlighted (light blue) and the disordered cytoplasmic outer ring is indicated (dashed lines).

(G) Close-up of a modeled spoke viewed along the 2-fold axis. Connector helices are colored gold.

(H) The spoke contains two domains, as indicated by dashed lines (gap), with distinctive functions. The Nup color palette reflects their distribution within the inner (green), adaptin-like (pink-red), and membrane-interacting (blue) layers.

(I) A thin slab viewed along the central 2-fold axis reveals a vertical separation of the outer spoke domain (dashed lines; also see Figure 3). Relevant scale bars are indicated on the panels.