Figure 3.

Footprints of tRNAs in the various functional complexes. Lane numbers correspond to (1) empty ribosomes; (2) ribosomes carrying MFK-mRNA and ${\text{tRNA}}_{\text{f}}^{\text{Met}}$; (3) ribosomes carrying MFK-mRNA, ${\text{tRNA}}_{\text{f}}^{\text{Met}}$ and AcPhe-tRNA^Phe; (4) ribosomes with MFK-mRNA, ${\text{tRNA}}_{\text{f}}^{\text{Met}}$, AcPhe-tRNA^Phe and EF-G*GTP; (A, C, G, U) correspond to sequencing lanes, (K) to the unmodified rRNA. Modification with kethoxal was used in (A), CMCT in (B) and DMS in (C). Primers complementary to the 23S rRNA positions 2281–2301 (A), 2649–2667 (B) and 16S rRNA positions 1440–1458 (C) were used for the extension reactions. Primer extension stops corresponding to the nucleotides protected by tRNA are indicated, together with their tRNA binding site specificity.