Nuclear RNP-particles bearing rapidly-labeled heterogeneous RNA from pea embryos

Ribonucleoprotein (RNP)-particles were extracted from the nuclei-enrichedfraction of pea embryos which were pulse-labeled with ³H-uridineor ₃H-adenosine. These nuclear RNP-particles sedimented heterodispersedlythrough a KCl-Mg-containing sucrose gradient with rather discretepeaks of 67–71, 53–55, 41–44, 33–35and 20–22S. These complexes were obtained even when thesynthesis of ribosomal RNA was inhibited by actinomycin D. Thelabeled RNA from the nuclear extracts, which contained theseRNP-particles, was shown to be heterodisperse RNA. (Received June 7, 1976; )