Cytoplasmic p53 polypeptide is associated with ribosomes

Beatriz M A Fontoura, Cesar A. Atienza, Elena A. Sorokina, Takashi Morimoto, Robert B. Carroll

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

Our previous finding that the tumor suppressor p53 is covalently linked to 5.8S rRNA suggested functional association of p53 polypeptide with ribosomes. p53 polypeptide is expressed at low basal levels in the cytoplasm of normal growing cells in the G(t) phase of the cell cycle. We report here that cytoplasmic wild-type p53 polypeptide from both rat embryo fibroblasts and MCF7 cells and the A135V transforming mutant p53 polypeptide were found associated with ribosomes to various extents. Treatment of cytoplasmic extracts with RNase or puromycin in the presence of high salt, both of which are known to disrupt ribosomal function, dissociated p53 polypeptide from the ribosomes. In immunoprecipitates of p53 polypeptide-associated ribosomes, 5.8S rRNA was detectable only after proteinase K treatment, indicating all of the 5.8S rRNA in p53-associated ribosomes is covalently linked to protein. While 5.8S rRNA linked to protein was found in the immunoprecipitates of either wild-type or A135V mutant p53 polypeptide associated with ribosomes, little 5.8S rRNA was found in the immunoprecipitates of the slowly sedimenting p53 polypeptide, which was not associated with ribosomes. In contrast, 5.8S rRNA was liberated from bulk ribosomes by 1% sodium dodecyl sulfate, without digestion with proteinase K, indicating that these ribosomes contain 5.8S rRNA, which is not linked to protein. Immunoprecipitation of p53 polypeptide coprecipitated a small fraction of ribosomes. p53 mRNA immunoprecipitated with cytoplasmic p53 polypeptide, while GAPDH mRNA did not. These results show that cytoplasmic p53 polypeptide is associated with a subset of ribosomes, having covalently modified 5.8S rRNA.

Original languageEnglish (US)
Pages (from-to)3146-3154
Number of pages9
JournalMolecular and cellular biology
Volume17
Issue number6
DOIs
StatePublished - Jun 1997

    Fingerprint

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this

Fontoura, B. M. A., Atienza, C. A., Sorokina, E. A., Morimoto, T., & Carroll, R. B. (1997). Cytoplasmic p53 polypeptide is associated with ribosomes. Molecular and cellular biology, 17(6), 3146-3154. https://doi.org/10.1128/MCB.17.6.3146