Figure 4.

Schematic of coordinated ATP hydrolysis and nucleotide exchange observed in seven states in the substrate-bound human 26S proteasome [11]. Three principal modes are depicted here, with Modes 1, 2, and 3 featuring hydrolytic events in two oppositely positioned ATPases (yellow and blue), in two adjacent ATPases (orange and violet) and in one ATPase at a time (forest green), respectively. The RPT subunits with their pore-1 loops on the top and bottom of the pore-loop staircase are labeled “Top” and “Bottom”, respectively, which are consistent with Figure 3c.