Figure 4.

(A) Effect of Mg²⁺ on the gel mobility shifts of (dbd)Fos–Jun bound to differently phased linear DNA isomers. The Mg²⁺ concentration refers to that contained in the gel and running buffer. The phasing numbers 11, 15, and 19 refer to AP-1 molecules hcgDNA11, hcgDNA15, and hcgDNA19, except in the A-tract site DNAs, where the phasing refers to molecules AtractDNA11, AtractDNA15, and AtractDNA19. The mobilities of the protein–DNA complexes relative to free DNA are normalized relative to each other. The amplitude is the difference between the maximum and minimum relative mobility values. (B) Linear relationship between relative gel mobility amplitude and Mg²⁺: comparison of Fos–Jun–DNA complexes and A-tract site DNA. The error bars represent the standard deviations for an average of at least 3 data points.