Invitro Stimulation Of Nucleolar And Nucleoplasmic Rna Polymerases In Calf Uterus

Two types of RNA polymerases have been isolated from calf uterus. One of them, Nucleolar RNA polymerase, is stimulated by the 5 S oestradiol fraction. The other, Nucleoplasmic RNA polymerase, is not stimulated by the same fraction. We examined the variation in activity of purified nucleoplasmic RNA polymerase as a function of the level of phosphorylation of the acidic nuclear proteins in reconstituted chromatin from calf thymus DNA. The activity of the Nucleoplasmic RNA polymerase varies in the same way as the level of the phosphorylation of the acidic proteins used to reconstitute the chromatin. Yet neither in vivo nor in vitro was oestradiol found to increase cyclic AMP level in the uterus. Moreover, IP biosynthesis induced by oestradiol is blocked by Actinomycin D and Cordycepin. The part played by IP in the transcription process is discussed.