FIGURE 1.
Structural comparison of U and Ψ and proposed role of decreased recognition by release factors. (A) Chemical structure of U and Ψ. Partial charge is labeled for each atom and calculated dipole moments of the two bases (debye, or D) are shown with arrays. (B) Recognition of U in a nonsense codon by RF1 (PDB code: 3D5A) and RF2 (2WH3). (C) Comparison of attractive dipole moment between the release factor protein and the nucleobase, when either a U or Ψ (assuming Ψ occupies the same position as U) is present in the active site of RF1. The extra water molecule present only with Ψ-modified nonsense codons is also shown.
