[Protein composition of chromatin fractions differing in their attachment to nuclear structures at low ionic strength].
Rat livers were disrupted in the TMS buffer (10 mM Tris-HCl, pH 7.6, 5 mM MgCl2, 0.25 M sucrose +70 microM beta-mercaptoethanol) and the nuclei were purified by sedimentation through 2.2 M sucrose with the same components as in TMS. Then the nuclei were resuspended and washed 3 times in TMS. After that the nuclei were resuspended to 1 mg DNA per ml in TM buffer (10 mM Tris-HCl, pH 7.6, 0.2 mM MgCl2) followed by centrifugation at low speed. About 60% of total nuclear DNP was recovered by this extraction. The protein/DNA ratio in the extracted chromatin fraction (DNPs) was about 1.1. The bulk of the non-extracted in TM residual chromatin fraction was released from the nuclear pellet after treatment with micrococcal nuclease. This matrix-associated chromatin fraction (DNPm) is significantly enriched in non-histone proteins as compared with the DNPs; hence the protein/DNA ratio of DNPm is at least two times higher than that of DNPs. The protein components of DNPs are represented by five histones containing negligible non-histone admixture. One of them was identified as protein A24, another--as non-dissociated from DNA in 0.6 M NaCl acid-soluble protein with m. w. of about 42,500. The possible structural features of these two distinguishable chromatin fractions are discussed.
D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure*; D002843:Chromatin / Q000648:ultrastructure*; D002868:Chromosomal Proteins, Non-Histone / Q000302:isolation & purification; D003852:Deoxyribonucleoproteins / Q000302:isolation & purification*; D008099:Liver / Q000032:analysis / Q000648:ultrastructure; D008970:Molecular Weight; D009698:Nucleoproteins / Q000302:isolation & purification*; D009994:Osmolar Concentration; D051381:Rats
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D003852:Deoxyribonucleoproteins; D009698:Nucleoproteins
Belkovyĭ sostav fraktsiĭ khromatina, razlichaiushchikhsia po sviazy s iadernymi strukturami v usloviiakh nizkoĭ ionnoĭ sily.