Fig. 6: SMAX1 stabilises ASK1–MAX2–HTL7 for ubiquitination.
A Cryo-EM density reconstructed from the tail clusters of one variability eigenvector from 3D variability analysis (3DVA). Proteins and domains are coloured as in Fig. 1. Arrows depict ASK1 motion and correspond to Supplementary Movie 1. B Same as in panel A, but rotated 90°. The MAX2 CTH is coloured blue and further indicated with a white arrow. C, D Model of a complete A. thaliana SCF–HTL7 ubiquitination complex in the resting (panel C) and retracted (panel D) ASK1 state. The ASK1–MAX2–HTL7–SMAX1 complex is coloured as in Fig. 1. CUL1 is coloured white, its Nedd/RUB modification is coloured pale pink. RBX1A is coloured light blue. UBC8 is coloured bright yellow. Ubiquitin is coloured orange. Arrows show the relative motion between resting and retracted states. E The transposition of SMAX1D2 in the resting (dark pink) and retracted (light pink) ASK1 conformations and the proximity to the E2 active site and ubiquitin. The conserved lysine residues of SMAX1D2 are coloured grey, shown as sticks, and labelled. The distance between resting and retracted states are shown as dotted lines and labelled. The gradient arrow indicates the relative motion between the two states. The E2 active site cysteine is coloured grey and shown as sticks. F Model of the 2:2 ASK1–MAX2 dimer fit in cryo-EM density (EMD-62414). Coloured as in Fig. 1.
