Fig. 2.
Structure of Mediator Head module–CTD complex. (A) Secondary structure representation of the Head module (green) superimposed on weighted electron-density map of the Head alone (2FO-FC; blue mesh), contoured at 1.25 σ. Difference map showing electron density for the CTD (brown mesh), calculated with Fsoak-Fnative amplitudes and MIRAS phases, contoured at 2.5 σ. CTD model encompassing almost four heptapeptide repeats is shown in stick representation (yellow). (B) Same as A rotated 90° around the vertical axis. (C) Close-up view of CTD interaction region bounded by dashed box in B. (D) CTD model and density from C shown with an aligned section of unmodified CTD peptide (β-turn) from high-resolution crystal structure (PID: 3D9O).