Figure 5.

Relative affinities of E4BP4 and the three PAR proteins for an optimal binding site (ATTACGTAAC). A constant amount of protein was incubated with increasing amounts of a radiolabeled probe. After gel electrophoresis and autoradiography (top panels), the radioactive bands corresponding to the bound and free forms were quantitated. The concentration of the bound probe was plotted against the total input probe to show saturation curves (middle panels). These data also were plotted by the method of Scatchard to determine the Kd values (bottom panels). The slope of the best-fit line is equal to −1/Kd. The correlation coefficients (R²) are indicated in the bottom panels.