Figure 4. ATP hydrolysis drives initial three steps of substrate translocation through the AAA-ATPase channel.

a, Side-by-side comparison of the Rpt1-Rpt2 dimer conformations in four sequential states that undergo a complete cycle of ATP hydrolysis and exchange in the Rpt1-Rpt2 dimer. Structures are aligned against the CP to show their conformational changes relative to the CP gate. Tyrosine residues in the pore-1 loops are shown in stick representation and highlighted with transparent sphere representation. Substrate is shown in red in stick representation. b, Schematic representation of the cascade of ATP hydrolysis and nucleotide exchange required to implement the transition from E_B to E_D1.