(A) View of the 70S ribosome from the 30S perspective, depicting the distinct intersubunit and 30S head rotations. (B) “Top” view of 70S ribosome showing the swiveling motion of the 30S head domain. Each line of movement represents distance between phosphorus atoms of the corresponding nucleotides of 16S rRNA from non-rotated [blue, PDB entries 2WDK,39] and rotated [purple, PDB entry 3SFS,23] ribosomes, with the two structure aligned to the same coordinate according to the 50S subunit120. Wheat, 23S rRNA; brown, large subunit proteins; magenta spheres, 50S components of intersubunit bridges in the classic-state (non-rotated) 70S ribosome.