FIG. 7.
ChIP assay. ChIP was used to assay the association of myc-p45 and myc-p45 (K368) with the β-like globin locus in transfected K562 cells. (A) Map of the globin locus and the regions analyzed for p45/NF-E2 binding. (B, C, D, E, F, and G) DNAs precipitated from K562 cell transfected with pEF-myc (gray-shaded bars), pEF-myc-p45 (black bars), and pEF-myc-p45 (K368R) (white bars), respectively, were analyzed by PCR using primers specific for HS1 (B), HS2 (C), HS3 (D), and HS4 (E) of β-LCR, two intergenic regions (region a [panel F] and region b [panel G]), and the β-actin gene. The samples of the input (In) and those precipitated with the use of anti-p45 (p45), anti-myc (myc), and preimmune serum (pre), respectively, are individually indicated underneath the gel panels. The DNA amounts used for PCR were determined by the intensities of the β-actin signals. The PCR signals were first normalized to those from the β-actin region. The different target/β-actin ratios were then further normalized again the target/β-actin ratios of the input samples and used to plot the histographs. The relative intensities of the positive signals were given as the increases (fold) over those from the preimmune samples. Each histogram consists of averages of data derived from two to three sets of PCR analysis conducted with the use of chromatin DNAs precipitated from at least two different K562 pools. The differences (fold) are given as means ± standard errors of the means.