Translocation of nucleolar phosphoprotein B23 ( 37kDa pI 5.1) induced by selective inhibitors of ribosome synthesis

Yat Ming Yung, Harris Busch, Pui Kwong Chan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

141 Citations (Scopus)


To elucidate the possible role of nucleolar phosphoprotein B23 in ribosome synthesis, drugs which inhibit the processing of ribosomal RNA were employed. After treatment with actinomycin D, toyocamycin or high doses of α-amanitin, a uniform nucleoplasmic fluorescence was observed. Low doses of α-amanitin and the protein synthesis inhibitor puromycin and cycloheximide had no effect on protein B23 translocation. By ELISA immunoassay, there was a 60% decrease in the amount of protein B23 in the nucleoli of the actinomycin D-treated cells as compared with the control nucleoli. Conversely, the amount of protein B23 in the nucleoplasm (excluding nucleoli) was 3-fold higher in the actinomycin D-treated cells. Preribosomal ribunucleoprotein particles (pre-rRNPs) were extracted from isolated nucleoli of Novikoff hepatoma ascites cells and fractionated on sucrose density gradients. Protein B23 was found co-localized with the pre-rRNPs as determined by ELISA assays which agrees with previous studies. The proteins in these 80 S and 55 S pre-ribosomal ribonucleoprotein particles were fractionated by 10% gel electrophoresis. Immunoblots showed protein B23 was present in both pre-rRNPs.
Original languageEnglish
Pages (from-to)167-173
Number of pages7
JournalBBA - Gene Structure and Expression
Issue number4
Publication statusPublished - 18 Dec 1985
Externally publishedYes


  • (HeLa cell)
  • Nucleolus
  • Phosphoprotein B23
  • Protein translocation
  • Ribosome synthesis

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Genetics
  • Structural Biology
  • Medicine(all)

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