Figure 1.
Ratchet-like motion and associated L1 stalk motion accompanying the movement of tRNA. Cryo-EM maps of Escherichia coli 70S·MFTI-tRNAIle–puromycin complexes before (a) and after (b) binding of EF-G•GDPNP (a non-hydrolysable GTP analogue) [26]. The L1 stalk of the 50S subunit is ‘open’ before (a) and closed after (b) binding of EF-G. (c) Conformational change of L1 stalk, which moves the tRNA from P/E (b) into E/E (a) position. Landmarks: L9, ribosomal protein L9; L2, protein L2; H76, helix 76 from the 23S rRNA; L1, L1 protuberance or stalk in the 50S subunit. (Reproduced with permission from [26].)