Figure 2. Kinetic analysis of the interactions of different TIAR constructs with U-rich RNA using SPR. The binding of (A) TIAR1, (B) TIAR2^S, (C) TIAR12^S and (D) TIAR2^L to a U-rich RNA is shown. Biotinylated RNA was captured on SA-coated sensor chip and increasing concentrations of protein were injected over the surface. Injections were performed for 120 sec (association phase), followed by a 300 sec flow of running buffer to assess dissociation. The experiments were conducted in duplicate and showed good overlap. The red line represents the binding responses for injections of protein analyte at specified concentration over the RNA surface. The kinetic data were fit by a 1:1 Langmuir binding model. Mass transport effects were not evident. The black curves superimposed on top of the sensor grams represent the model fitted curves. The rate constants k_a and k_d were determined simultaneously as global fitting parameters from which the K_D was determined. The resulting parameter values are given in Table 1.