Fig. 5.

Association of ERα, C/EBPβ, and SP1 with the E2-responsive sequence of hPIII promoter of human prolactin receptor gene. (A) A schematic presentation of biotinylated DNA probes used in the DAPA experiment. DNA sequences within the hPIII promoter and putative C/EBPβ and SP1 binding motifs are indicated. (B) Wild-type and mutant probes (X; sequences are indicated in lowercase letters) were incubated together with in vitro-translated wild-type human SP1-V5, ERα-V5, and C/EBPβ-V5. Proteins associated with each DNA probe were detected with Western blot analysis using V5 antibody. SP1-V5, solid and dotted arrows; ERα-V5, open arrow; C/EBPβ-V5, striped arrow. *, SP1 protein variant translated from an alternative ATG codon. Results are representative of at least three separate experiments.