[Transcription and the composition of chromatin isolated from rat liver cells after cortisone administration]

The effect of removal of various protein fractions on the patterns of transcription of the chromatin isolated from rat liver nuclei after cortisone administration has been studied. The RNA synthesized in vitro on the protein-depleted chromatin templates was investigated by competitive hybridization technique with the nuclear RNA synthesized in vivo. Extraction of chromatin with 0.7 M NaCl (removal of histone H1 and a part of loosely bound nonhistone proteins) did not interfere with the synthesis of the hormone-specific RNA population on chromatin templates. However, treatment of chromatin with 1.0 M NaCl fully eliminated the hormone-related pattern of transcription. Electrophoretic analysis demonstrated that the fractional composition of chromatin proteins is changed under the action of cortisone. An additional protein fraction specific for the hormone-activated chromatin with a lower electrophoretic mobility than H1 histone was found by electrophoresis at pH 2.7. Using the method of SDS electrophoresis, the additional subfraction of H1 histone was observed and the amount of protein located between H1 and H3 histones increase as the result of cortisone injection.