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. 2012 Nov 27;109(50):20391–20394. doi: 10.1073/pnas.1218999109

Fig. 2.

Fig. 2.

Rotation of the 30S subunit head during EF-G–catalyzed translocation. (A) mRNA translocation, as followed by quenching of fluorescence of a pyrene dye attached to position +9 of mRNA (24). (B) Rotation of 30S subunit head, followed by changes in FRET efficiency between donor Alexa 488 and acceptor Alexa 568 probes attached to position 101 of S11 and position 11 of S13 for the S11-D/S13-A pair (green) and position 108 of S12 and position 56 of S19 for the S12-D/S19-A pair (red). Pretranslocation 70S ribosome complexes were rapidly mixed with EF-G GTP at time = 0 and pyrene fluorescence (A) or Alexa 568 emission (B) were recorded (19). Each trace represents the average of 10 reactions. AU, arbitrary units; WT, WT unlabeled ribosomes.