title: Differing accessibility in chromatin of the antigenic sites of regions 1-58 and 63-125 of histone H2B.
abstract: Experiments with antibodies induced by separated fragments 1-58 and 63-125 of H2B histone indicated that the 1-58 portion of the molecule is much more accessible in chromatin than is the 63-125 region. In immunoabsorption and immunoelectron microscopic assays with bovine and chicken chromatins, anti-1-58 antibodies reacted with sheared or unsheared chromatin both at low ionic strength (1 mM Tris-HCl) and in 0.14 M NaCl. Anti-63-125 antibodies were bound only weakly by chromatin at low ionic strength and not at all in 0.14 M NaCl. Antibodies to whole H2B showed intermediate reactivity with chromatin in both assays. In tests of immunofluorescence with unfixed calf liver nuclei in suspension, anti-1-58 caused nucleolar as well as nucleoplasmic fluorescence, whereas anti-63-125 did not lead to detectable fluorescence; anti-H2B showed intermediate staining intensity. In control experiments, anti-H1 antibody was bound by chromatin at low ionic strength but not in 0.14 M NaCl; anti-H3 antibody was bound poorly under either condition.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002843:Chromatin / Q000648:ultrastructure*; D000939:Epitopes; D006657:Histones / Q000276:immunology*; D008854:Microscopy, Electron; D009707:Nucleosomes / Q000648:ultrastructure; D009994:Osmolar Concentration; D010446:Peptide Fragments / Q000276:immunology
chemical_list: D002843:Chromatin; D000939:Epitopes; D006657:Histones; D009707:Nucleosomes; D010446:Peptide Fragments