Matrix attachment sites in the murine α-globin gene

DNA sequences with a high affinity for nuclear matrix proteins have been identified and localized in the mouse α-globin gene. These matrix association regions (MARs) are adjacent, covering the first intron and part of the 5′-coding sequence. The binding sites are in close proximity to DNase I hypersensitive sites and other important signal sequences. The proteins of the nuclear lamina do not bind the α-globin gene MARs in the in vitro binding assay. The finding of MARs in the mouse α-globin gene creates an apparent paradox, since works from other authors and our results presented here indicate that this gene is not bound to the nuclear matrix in vivo. This contradiction is difficult to explain at present but different possibilities are accounted for in the text.