title: Tightly bound DNA-protein complexes representing stable attachment sites of large DNA loops to components of the matrix.
abstract: This study describes tightly bound DNA-protein complexes in DNA of matrices isolated from Friend erythroleukemia cells. When after radio-iodination of the associated proteins, such DNA is electrophoresed on agarose and the gel is subsequently subjected to autoradiography, the protein components of three or four complexes are visualized. Their two-dimensional electrophoretic analysis revealed that each possesses a simple but specific polypeptide composition, including a set of five non-histone proteins, characteristic for the matrix, and the core histones H3 and H4. Since the polypeptides dissociate from DNA by treatment with SDS, it is suggested that the linkage is not covalent. Reassociation and hybridization analysis of the DNA of the complexes indicated that it is enriched in highly repetitive, satellite sequences. The latter were found to be, to a great extent, similar to sequences localized at the base of large, dehistonized DNA loops obtained by high-salt extraction of isolated nuclei. Further experiments emphasized the complete conservation of this type of attachment throughout erythroid differentiation of Friend cells. It is proposed that the complexes represent attachment sites of basic, 30-100-kbp loop units of DNA.
authors.affiliation: Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia.
authors.forename: C
authors.initials: C
authors.lastname: Patriotis
authors.forename: L
authors.initials: L
authors.lastname: Djondjurov
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D004273:DNA, Neoplasm / Q000302:isolation & purification / Q000378:metabolism*; D004587:Electrophoresis, Agar Gel; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D006657:Histones / Q000302:isolation & purification / Q000378:metabolism; D007457:Iodine Radioisotopes; D004915:Leukemia, Erythroblastic, Acute; D051379:Mice; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D011865:Radioisotope Dilution Technique
chemical_list: D004273:DNA, Neoplasm; D006657:Histones; D007457:Iodine Radioisotopes; D009687:Nuclear Proteins