FIGURE 5.

The PIP motif of PabNucS is critical for the interaction with PabPCNA. A, for the competition experiment, sensorgrams were obtained after a 300-s injection of 300 nm PabNucS mixed with a range of PIP-peptide concentrations from 3 to 30 μm or with 10 μm control peptide. Controls consisted in the injection of 10 μm PIP-peptide and 10 μm of a noninteracting control peptide alone. B, fits of the calculated sensorgrams (red) of the interaction between immobilized PabPCNA and PIP-peptide, according to a simple 1:1 model, to the experimental data (black) obtained after injection of a concentration range from 81 nm to 1 μm PIP-peptide. C, fits of the calculated sensorgrams (red) of the interaction between immobilized PabPCNA and PabNucS, according to a complex model (see ”Experimental Procedures“), to the experimental data (black) obtained after injection of a concentration range from 100 nm to 2.7 μm PabNucS.