Fig. 5. H4 acetylation at the enhancer blocker, the enhancer and the promoter is present only in lysozyme-expressing cells and is further induced by T3 additon. (A) Nucleosomal structure in the upstream lysozyme chromatin (Huber et al., 1996) is indicated by the position of hypersensitive sites for micrococcal nuclease digestion (arrows). Enhancer factor binding sites for PU.1 and C/EBP (Faust et al., 1999) and binding sites for CTCF and TR on the F1/F2 element are indicated. Nucleotide positions for the amplicons 1 to 5 used for the ChIP assay in (B) and (C) are indicated. Amplicon 6 covers the promoter region (–182/–77; data not shown). Chromatin immunoprecipitation of acetylated histone H4 from HD37 cells and HD11 cells are given in (B) and (C), respectively. Fold enrichment or fold depletion is the ratio of the PCR signal from the Ab-precipitated chromatin relative to that from the input chromatin (see Materials and methods). The x-axis shows the amplicon positions relative to the lysozyme upstream region, as indicated at the bottom of the graph.