Figure 1.

Maps of the human β-globin locus, DNA constructs, and the PYR factor binding site upstream of the δ-globin gene. (A) The human β-globin locus on chromosome 11. The LCR is characterized by four erythroid-specific DNase I hypersensitive sites (arrows) upstream of the embryonic ɛ gene. There are duplicated fetal genes (^Gγ and ^Aγ), a pseudogene (ψβ), and two adult genes (δ and β). The vertical line upstream of ^Aγ marks a HindIII site. (B) Map of the μLCR^Aγψβδβ (wt) mini-locus construct used in transgenic mice. It consists of a 2.5-kb cassette containing each of the four LCR DNase I hypersensitive sites (μLCR) linked to a 29-kb HindIII–KpnI restriction fragment containing the ^Aγ through β genes. Vertical lines upstream of the δ gene delineate the 511-bp BsaBI–BsmI restriction fragment removed from the construct to create μLCR^Aγψβδβ-Δ (Δ). (C) Expanded view of the deleted BsaBI–BsmI fragment showing the long pyrimidine-rich domain (rectangle Y⋅R) and the region footprinted by PYR factor. The segment from the BsaBI site to a Sau3AI site (S) has been analyzed for transcription factor binding sites by DNase I footprinting.