Gene-specific differences in the supranucleosomal organization of rat liver chromatin.
Rat liver chromatin was separated into a solubilized portion and insoluble nuclear material, and the solubilized portion was fractionated by sucrose gradient sedimentation. The chromatin encompassing three transcribed genes (albumin, tryptophan oxygenase, and alpha-fetoprotein), which are expressed at very different levels, partitions preferentially with insoluble nuclear material and possesses a disrupted nucleosome structure. On the contrary, the chromatin encompassing three inactive genes fractionates into the solubilized chromatin portion and exhibits a canonical nucleosome repeat structure. By sucrose gradient sedimentation, all size classes of inactive chromatin particles are found to contain internal cleavages in the linker region between nucleosomes; they are probably held together by histone H1 and mono- and divalent cations. When the chromatin encompassing two flanking sequences of the tyrosine aminotransferase gene is studied, the 0.35-kilobase upstream-located chromatin exhibits features of active genes, while the 2.55-kilobase upstream-located chromatin partitions preferentially with solubilized chromatin and sediments in internally cleaved particles.
D000818:Animals; D002458:Cell Fractionation / Q000379:methods; D002499:Centrifugation, Density Gradient / Q000379:methods; D002843:Chromatin / Q000648:ultrastructure*; D003001:Cloning, Molecular; D005796:Genes; D006728:Hormones / Q000235:genetics; D008099:Liver / Q000378:metabolism / Q000648:ultrastructure*; D008297:Male; D009707:Nucleosomes / Q000648:ultrastructure*; D051381:Rats; D011919:Rats, Inbred Strains; D012709:Serum Albumin / Q000235:genetics; D014158:Transcription, Genetic; D014366:Tryptophan Oxygenase / Q000235:genetics; D000509:alpha-Fetoproteins / Q000235:genetics
D002843:Chromatin; D006728:Hormones; D009707:Nucleosomes; D012709:Serum Albumin; D000509:alpha-Fetoproteins; D014366:Tryptophan Oxygenase