Extended Data Fig. 11: SPC-binding sites evidenced in INT1.
From: Structural basis of early translocation events on the ribosome
a, SPC-binding site (red) on the SSU between the head (purple) and body (blue) domains beneath the SSU P site. b, Zoom-in of the primary SPC-binding site showing that the convex face of SPC sits in the major groove of h34 (purple, between A1193 and G1064) and that the concave face of SPC sits between h28 (dark blue, G1387) and uS5 (cyan). Lys26 of uS5 reaches to interact with the h28 phosphate G1387. c, Overlay of the SSU SPC-binding pocket for INT1 (coloured) and INT2 (white), showing collapse of the SPC binding site and reorientation of Lys26 during SSU head-domain swivel. SPC shown in ball-and-stick and transparent-sphere representation. Distance changes for h28 (G1387 C1′), h34 (A1196 C1′) andh35 (C1066 C1′) are indicated. d, Electron density indicative of a second SPC-binding site near the exit tunnel of the LSU between uL22 and nucleotides G488 and A1284. Threshold σ = 6. e, Overlay of the SSU from PRE-C (light grey), PRE-H2* (light blue), PRE-H1 (blue), INT1 (light purple), INT2 (purple) and POST (dark grey) aligned on the SSU body domain to illustrate head-domain swivel. See also Supplementary Video 6.
