Fig. 2.

Cognate interactions between ${\text{tRNA}}_{\text{GGC}}^{\text{Ala}}$ and the GCC mRNA codon. (A) Overview of the bacterial 70S ribosome containing a P-site tRNA^fMet and an A-site ${\text{tRNA}}_{\text{GGC}}^{\text{Ala}}$ bound to a GCC codon. (B) Zoomed-in view of the anticodon stem−loop of ${\text{tRNA}}_{\text{GGC}}^{\text{Ala}}$ showing three Watson–Crick pairings between the anticodon and the codon. The +1 mRNA numbering starts in the P site, with the A-site nucleotide positions labeled as +4, +5, and +6. (C) The A32−U38 pairing forms a well-ordered Watson–Crick base pair. The 2F_O−F_C electron density map (gray mesh) is contoured at 1.0σ.