In vivo assembly of newly synthesized histones.

摘要: Following a labeling period of 2 min, HeLa histones continue to accumulate in chromatin for 10 indicating the presence histone pool. During accumulation period, H2A and H2B enter immediately, while entry H3 H4 is more prolonged. Association newly synthesized core with does not necessarily indicate assembly. When 2-min [3H]lysine-labeled exposed 0.45 M NaCl, nearly half are dissociated, mature stable. 70% salt stable remain polynucleosomes. About 30% H2B, 50% H4, all labile; thus, both new nucleosomal salt-labile nonstoichiometric. Pulse-labeled trypsin-sensitive than histones. salt-labile, removed, remaining proteins have same trypsin sensitivity as bulk protein. Examination tryptic peptides indicated that increased was due complete destruction loosely associated which undergo lag prior The altered order appearance two stripped, assembled nucleosomes indicates conformation these particles different from chromatin.