FIG. 8.

Modest cooperative DNA binding by E47 and PDX1. (A) The homeodomain of PDX-1 (160 pg; lanes 1, 3 to 10, and 12) and the bHLH domain of E47/Pan1 (6 ng; lanes 2 to 11) were incubated with the ³²P-labeled rat insulin E2A3/4 probe (EA; lanes 1 to 6) or with a similarly labeled probe containing a 15-bp insertion between the E and A binding sites (EA-I; lanes 7 to 12) and analyzed by EMSA. (B) The complexes from at least five independent EMSAs were quantified with a phosphorimager, and the cooperativity index was calculated as defined in Table 2. HMG I(Y) experiments were performed as for Fig. 9, with 37 ng (+) and 110 ng (++) of HMG I(Y). Mean ± standard error of the mean is shown.