Structure of pp32, an acidic nuclear protein which inhibits oncogene- induced formation of transformed foci

Tseng Hui Chen, Jonathan R. Brody, Feodor E. Romantsev, Jun Ge Yu, Amy E. Kayler, Elizabeth Voneiff, Francis P. Kuhajda, Gary R. Pasternack

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

pp32 is a nuclear protein found highly expressed in normal tissues in those cells capable of self-renewal and in neoplastic cells. We report the cloning of cDNAs encoding human and murine pp32. The clones encode a 28.6- kDa protein; approximately two-thirds of the N-terminal predicts an amphipathic α helix containing two possible nuclear localization signals and a potential leucine zipper motif. The C-terminal third is exceptionally acidic, comprised of approximately 70% aspartic and glutamic acid residues; the predicted pI of human pp32 is 3.81. Human and murine pp32 cDNAs are 88% identical; the predicted proteins are 89% identical and 95% similar. Although the structure of pp32 is suggestive of a transcription factor, pp32 did not significantly modulate transcription of a reporter construct when fused to the Gal4 DNA-binding domain. In contrast, in cotransfection experiments, pp32 inhibited the ability of a broad assortment of oncogene pairs to transform rat embryo fibroblasts, including ras + myc, ras + jun, ras + E1a, ras + mutant p53, and E6 + E7. In related experiments, pp32 inhibited the ability of Rat 1a-myc cells to grow in soft agar, whereas it failed to affect ras- induced focus formation in NIH3T3 cells. These results suggest that pp32 may play a key role in self-renewing cell populations where it may act in the nucleus to limit their sensitivity to transformation.

Original languageEnglish (US)
Pages (from-to)2045-2056
Number of pages12
JournalMolecular biology of the cell
Volume7
Issue number12
DOIs
StatePublished - Dec 1996
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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