Figure 4.

Results of isothermal titration calorimetry experiments for the PAZ complex with (A) native RNA and (B) modified RNA. The experiments were conducted under the following conditions: 56 μM Ago2 PAZ and 600 μM RNA in a buffer composed of 5 mM HEPES pH 7.5, 150 mM KCl, 10% glycerol and10 mM DTT. RNA was added to the protein solution by 28 to 33 1.2 μL injections at 25°C. Note the 1:1 stoichiometry of the complexes, consistent with the structural models depicted in Figure 1A.