FIG. 2.

DIMM transactivates the PHM via the subsets of E boxes in its first intron and binds the E1 box directly. (A) A schematic of the first PHM intron indicating the positions of seven E boxes, E1 to E7 (see Table 1 for sequences of wild-type and mutated E boxes). Arrows indicate the original orientation of the DNA fragments. (B) Activity of the two constructs and the control vector diagrammed in panel A. In response to DIMM cotransfection, the first intron of PHM displays strong enhancer activity when fused to a heterologous simian virus 40 (SV40) promoter. (C to F) Effects on PHM transactivation by DIMM following site-directed mutagenesis of different E-box sequences within PHM's first intron. A gray box indicates a particular E-box mutation site. Ratios were calculated by dividing values resulting from dimm cotransfection by those resulting from no cotransfection. The histogram represents the means and standard errors of the means of the results. *, P < 0.05; **, P < 0.01. P values in comparison to the wild type were obtained by Student's t test.