Figure 7. Architecture of the Mammalian Transport Channel Formed by the Nup62·Nup54·Nup58 Complex.

(A) Cartoon representation of the transport channel with color coding and representation of the midplane ring as in Figure 6D. Nup62·Nup54 heterotrimers are shown as vertical cylinders colored in gray (two Nup62 molecules) and cyan (one Nup54). The linker regions of the Nup54 molecules are represented as cyan and green transparent tubes. See also Movie S3.

(B) Schematic representation of 1/8 segment of the transport channel. Nup54·Nup58 heterotetramers are shown as boxes in same color coding as in (A). Nup54 clamps are shown as cyan hooks. The Nup62·Nup54 heterotrimer is represented by three cylinders (Nup62 and Nup54 in gray and cyan, respectively). Dashed lines represent linker regions.

(C) Schematic arrangements of FG repeat regions of Nup58 in the transport channel. Both N-terminal (longer ribbons) and C-terminal (shorter ribbons) FG regions are colored pink or red. Dashed pink and red lines indicate N-terminal α-helical regions of Nup58 that connect Nup58 to N-terminal FG regions. Nup62 and part of Nup54 molecules are depicted in background.

(D) The position of FG repeat regions of Nup54 and Nup62. The N-terminal FG regions (ribbons) of Nup54 (cyan) and Nup62 (gray) project to cytoplasmic and nucleoplasmic sides of the midplane ring. FG regions of Nup58 are shown in the background (pink).

(E) The transport channel (as shown in A) embedded in the NPC. The core of the NPC is schematically shown as concentric cylinders and is anchored in the nuclear envelope. Attached to the core are a cytoplasmic ring with filaments and a nucleoplasmic ring with the “nuclear basket.”