The incorporation of newly synthesized RNA into nuclear ribonucleoprotein particles after oestrogen administration to immature rats.

Ribonucleoprotein particles, known as informofers or heterogeneous nuclear ribonucleoprotein particles (hnRNA - protein), have been extracted from rat uterine nuclei and found to have properties similar to those characterized from other tissues. Incorporation of RNA precursors into the RNA of these particles is stimulated up to 8-fold by oestrogen administration to rats. When uteri are dissected from oestrogen-treated rats and incubated in vitro with radioactive RNA precursor, only the RNA in the ribonucleoprotein particles is synthesized at a rate faster than can be accounted for by increase in the uptake of precursor. This contrasts with previous studies where both hormone treatment an incorporation of radioactive precursor were performed in vivo and the synthesis of all RNA species was stimulated [Knowler, J.T. and Smellie, R.M.S. (1971) Biochem. J. 125, 605--614; Knowler, J.T. and Smellie, R.M.S. (1973) Biochem. J. 131, 689--697].