Fig. 2: TXNL1 binds the RS proteasome in multiple conformations through contacts with Rpn2 and Rpn10’s VWA domain.
From: Structural landscape of the degrading 26S proteasome reveals conformation-specific binding of TXNL1
a, Densities of the RS.1 26S proteasome bound to TXNL1’s PITH domain in the forward (left; PITH shown in orange) and backward (right; PITH shown in cyan) conformations. The forward position is identical to the location of the PITH domain on PS proteasomes, whereas the backward conformation is rotated by ~90°. RS.1 refers to a particular class of RS proteasomes that differ from RS.2 through a slight shift in the RP (Extended Data Fig. 7). b, Particle distribution of RS proteasomes with TXNL1 bound in the forward, backward or mixed conformations. Mixed conformations represent intermediate states because of PITH domain motions or particles with ambiguous probabilities of belonging to either conformation. c, Top left: atomic model of the RS.1 proteasome with the PITH domain (cyan) in the backward conformation. Right and bottom: zoomed-in views of specific interactions between the PITH domain and Rpn2, Rpn10’s VWA domain and Rpn8. The contacts with Rpn2 and Rpn10 strongly rely on ion pairs, whereas a polar–π interaction is at the center of the interface with Rpn8.
