Figure 3. Solution competition analysis of arrestin binding to synthetic peptides

The peptides 4P and Scr were immobilized on the surface of an F1 sensor chip at 180 RU and 188 RU, respectively. A: Arrestin (4 μM) was mixed with varying concentrations of 4P peptide as described in the Methods and injected over the surface of the chip to measure arrestin binding. The level of arrestin binding to Scr was subtracted from the binding to the 4P peptide. The data were analyzed by nonlinear regression analysis using the computer program GraphPad Prism. B: Arrestin (4 μM) was preincubated with each peptide at a concentration of 256 μM and subjected to surface plasmon resonance to analyze the binding to 4P and Scr peptides immobilized as described in A. The binding of arrestin to Scr was subtracted from the binding to 4P peptide and the values normalized to the binding of arrestin to the surface in the absence of competing peptide. These results are from two independent experiments that gave very similar results.