title: Accessibility of newly synthesized chromatin to histone acetylase.
abstract: Pulse-chase experiments with [3H]lysine-labeled tissue culture cells reveal that newly synthesized nucleosomal histones H2B, H3, H4 (and possibly H2A) in chromatin are more accessible to histone acetylase in vivo than are older, pre-existing histones. Thus, when rat hepatoma cells are first pulse-labeled and then incubated in medium containing n-butyrate which blocks histone deacetylation, these newly synthesized histones become acetylated to a far greater extent than do their older homologues. As judged by its increased susceptibility to acetylation, the new chromatin matures at a surprisingly slow rate, the estimated half-time for maturation being about 35 min. Based on this data, we suggest that newly synthesized chromatin is in a relatively extended, accessible conformation, and that it slowly returns to a more compact conformation as it matures.
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism*; D000818:Animals; D002843:Chromatin / Q000378:metabolism*; D051548:Histone Acetyltransferases; D007700:Kinetics; D008114:Liver Neoplasms, Experimental / Q000201:enzymology; D011487:Protein Conformation; D051381:Rats; D029701:Saccharomyces cerevisiae Proteins; D013379:Substrate Specificity
chemical_list: D002843:Chromatin; D029701:Saccharomyces cerevisiae Proteins; D000123:Acetyltransferases; D051548:Histone Acetyltransferases