Transcription is efficiently inhibited by DRB and α-amanitin.

(A) Schematic presentation of the murine β-globin locus. Red arrows and ellipses depict the individual HSs. The globin genes are indicated by black triangles. The white boxes indicate the olfactory receptor (OR) genes (5′OR1-6 and 3′OR1-4). Distances (roman numerals) are in kb counting from the site of initiation of the εy gene. (B) Primary RNA-FISH of DRB and α-amanitin treated cells. Red bars indicate percentage of cells expressing β-globin and green bars indicate percentage of cells expressing α-globin. Representative examples of images are shown. (C) Reduction of the active elongating form of RNAPII as detected by western blot. Top panel using an antibody against the RPB1 subunit of RNAPII (N20). IIO represent the phosphorylated form of RNAPII, IIA the unphosporylated form. Bottom panel using an antibody against the Ser2 phosphorylated CTD of RNAPII (H5). (D) RNAPII binding at the β-major gene and hypersensitive sites of the LCR. Enrichment is relative to amylase. Blue bars depict untreated samples, red bars DRB treated samples, green bars α-amanitin treated samples. (E) RNAPII binding at regulatory elements within the Rad23a locus upon DRB and α-amanitin treatment. Enrichment is relative to amylase. Blue bars depict untreated samples, red bars DRB treated samples and green bars α-amanitin treated samples. Error bars indicate standard error of mean.