Isolation and distribution of a Drosophila protein preferentially associated with inactive regions of the genome

Abstract

The distribution patterns of chromosomal proteins from Drosophila can be observed by immunofluorescent staining of the polytene chromosomes from larval salivary glands. We have purified a non-histone chromosomal protein of Mr = 69,000 molecular weight which has a high affinity for DNA with little sequence specificity. Immunofluorescent staining indicates that this protein is preferentially associated with the inactive portions of the genome, including the centric heterochromatin and the condensed bands within the euchromatic arms of the chromosomes. Observation of both the heat shock loci 87A and 87C and the developmentally regulated loci 74EF and 75B shows an inverse correlation between immunofluorescent staining for the Mr = 69,000 protein and for RNA polymerase. The presence of this protein appears to be correlated with the packaging of the chromatin in an inactive form.

The nucleosome map of the mammalian liver

“…Hp1 and trimethylated histone H3 lysine 9 (H3K9me3) are genomic markers of heterochromatin 23,24 . Following ChIP-Seq, we plotted the Hp1 distribution surrounding all Foxa2 binding sites and H3K9me3 sites.…”

High-mobility group protein HMG-I localizes to G/Q- and C-bands of human and mouse chromosomes.

“…In addition to variations in base composition, it is now generally acknowledged that the interactions of particular nonhistone chromatin (NHC) proteins with specific regions or sequences of DNA are also likely to be important determinants of mammalian chromosome staining and/or banding patterns (Babu and Verma, 1987;Sumner, 1982;Cartwright et al, 1982;and Comings, 1978). Indeed, a few examples have been reported of localization of certain NHC proteins to specific chromosome regions such as centromeres (Tharappel and Elgin, 1986;Earnshaw and Rothfield, 1985), telomeres (Gottschling and Zaiken, 1987), the nucleolar organizer region (Guldner et al, 1986), satellite DNA or A-Trich heterochromatin (Fleischmann et al, 1987;Solomon et al, 1986;Strauss and Varshavsky, 1984;Levinger and Varshavsky, 1982;Alfageme et al, 1980), to the base of DNA loops on metaphase chromosome scaffolds (Earnshaw et al, 1985), and to lampbrush chromosome loops (Roth and Gall, 1989). By comparison, little is known about the mechanism of mammalian chromosome G-banding or the manner in which particular NHC proteins might be involved in the chromatin structure in these regions (Babu and Verma, 1987;Sumner, 1982).…”