Figure 4. Induced fit in rRNA-protein interactions.

Different residues in a single 30S protein binding site are protected with different rate constants, when probed by X-ray footprinting. (a) Residues contacted by protein S4 in mature 30S subunits colored according to the rate of protection: red, ≥ 20s⁻¹; orange, 2–20 s⁻¹; green, 0.2 –2 s⁻¹; blue, 0.01 – 0.2 s⁻¹. (b) Residues contacted by protein S16, colored as in (a). Reproduced from Ref. ⁵⁵ with permission.