Non-histone chromosomal proteins. Their isolation and role in determining specificity of transcription in vitro.
We describe a method for fractionation of chromatin components by selective dissociation with salt in buffers containing 5 M urea in combination with cromatography on hydroxyapatite at 4 degrees C. This results in two histone and four non-histone fractions which are recovered in high yield and with minimal proteolytic contamination. Template capacity measurements of the isolated chromatins and pre-saturation competition hybridization experiments support the idea that a group of non-histone proteins activate the transcription of specific DNA sequences which were not transcribed from purified DNA to the same extent. In reconstitution experiments a non-histone protein fraction, NH4, prepared from lymphocyte chromatin by hydroxyapatite chromatography is shown to cause transcription in vitro of lymphocyte-specific RNA sequences. A subfraction with a molecular weight of 30 000 comprising 40% of the NH4 fraction protein is characteristic for this tissue and not found in liver chromatin.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D002467:Cell Nucleus / Q000032:analysis; D002843:Chromatin / Q000302:isolation & purification*; D004247:DNA / Q000302:isolation & purification; D006657:Histones / Q000302:isolation & purification*; D008099:Liver / Q000032:analysis; D008214:Lymphocytes / Q000032:analysis; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D011506:Proteins / Q000302:isolation & purification*; D012313:RNA / Q000096:biosynthesis; D013698:Templates, Genetic; D014158:Transcription, Genetic
D000596:Amino Acids; D002843:Chromatin; D006657:Histones; D011506:Proteins; D012313:RNA; D004247:DNA