Fig. 1.

Illustration of the structure of different parts of the 26S proteasome. (A) Transparent gray, ice blue, red, yellow, cyan, magenta, green, top blue, orange, mauve, and bottom blue denote, respectively, the non-ATPase regulatory subunits, the ubiquitin, the RPN11, the OB ring of the AAA+ motor, the substrate, the ATP-fueled AAA+ motor, and the $\alpha$7, β5, β5, $\alpha$7 system. The upper section (transparent gray, ice blue, red, yellow, cyan, magenta, and green) forms the 19S RP. The bottom section (blue, orange, mauve, and bottom blue) forms the 20S core particle. Two coiled coils of the AAA+ motor are omitted here for a better view of the ubiquitin-bound substrate. (B) Top view of the AAA+ motor. (C) Side view of the AAA+ motor.