Figure 3.

Structural features of the substrate-bound human 26S proteasome in different conformational states. (a) Conformational switching of the RP during the transition from state E_B (dark gray; PDB ID: 6MSE) to E_C1 (yellow; PDB ID: 6MSG), with the CP (gray) aligned. (b) Cutaway surface representations of the RP–CP interface in different states. The red dashed circles highlight the densities of the RPT C-terminal tails that are inserted into the α-pockets of the CP. (c) Schematics showing the relative locations of the pore-1 loops of six RPT subunits along the vertical axis. RPT subunits in ATP-bound (red), ADP-bound (green) and apo-like (blue) states are depicted alongside the substrate from top to bottom and subunits that are disengaged from the substrate are placed on the left side. States E_A1, E_A2 and E_C1 are omitted here, as their ATPase structures are identical to that of E_B and E_C2, respectively.