In vitro DNaseI footprint analysis of the β-globin intron-2 AT-rich region (ATR).

(A) Footprint of ATR sense strand probes protected by MEL cell nuclear extract showing footprints FT1 and FT2 with associated hypersensitive bases (small arrows) on the wild-type ATR fragment but not on the mGata-1/mOct-1 ATR fragment. ATGC indicates dideoxy sequencing ladders. (B) Footprint of the ATR antisense strand shows FT1 and FT2 on the wild-type ATR fragment but not the mGata-1/mOct-1 ATR fragment. (C) Location of FT1 and FT2 footprints in β-globin intron-2 aligned beside the reported AT-rich region and MAR. Gray ovals indicate footprints; block arrows, tracts of adenosine/thymidine–rich sequence; thin line, intron-2; thick lines, exons.