BINDING OF HMG-17 TO MONONUCLEOSOMES OF THE AVIAN BETA-GLOBIN GENE-CLUSTER IN ERYTHROID AND NON-ERYTHROID CELLS

The binding of HMG 17 to stripped core mononucleosomes containing DNA from the avian β-globln gene cluster was examined to determine whether binding in vitro in this developmentally-regulated gene domain was associated with transcriptional activity or DNasel-sensitivity in intact nuclei. Mononucleosomes were prepared from primitive and definitive stage embryonic red blood cells of chick embryos, adult reticulocytes, adult reticulocytes in which embryonic ρ{variant}-globin transcription was induced, and adult thymus cells. Preferential binding by HMG 17 to mononucleosomes containing the β-globin gene cluster was confined to erythroidderived mononucleosomes that contain the embryonic ε-globin gene, the adult β-globin gene, and DNA sequences located between these two genes, but not to those that contain the embryonic ε-globln gene. Comparison of these results to the known patterns of transcription and DNasel-sensitivity within the β-globin gene cluster shows that HMG 17 binding, although tissue-specific, does not correlate directly with either DNasel-sensitivity or active gene transcription, but is dependent on other factors present in core mononucleosomes from this active gene domain. © 1990 Oxford University Press.