title: Histone neighbors in nuclei and extended chromatin.
abstract: Histone neighbors in compact and extended chromatin have been investigated by cross-linking histones in nuclei and in nucleohistone extended with 6 M urea, using the bifunctional reversible reagent methyl-4-mercaptobutyrimidate (MMB). Similar histone dimers are found in both conformational states of chromatin. The dimers most frequently found are H2b-H2a, H2b-H3 and H3-H2a; dimers found less frequently are H3-H4, H3-H3 and H2b-H4. More H3-H3 is found in nuclei than in extended chromatin. H1 is found predominantly as poly-H1, although it can be cross-linked to H2b or H3. After reaction with MMB, native compact chromatin is no longer extendable in 6 M urea, which shows that the reagent is capable of linking together histones holding the chromatin in a compact conformation. Thus the histone propinquity in extended chromatin mimics and intimate histone associations in compact chromatin.
mesh_terms: D002467:Cell Nucleus / Q000032:analysis*; D002843:Chromatin / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D006657:Histones / Q000032:analysis*; D007094:Imides / Q000494:pharmacology; D011487:Protein Conformation; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D014508:Urea
chemical_list: D002843:Chromatin; D006657:Histones; D007094:Imides; D013438:Sulfhydryl Compounds; D014508:Urea