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Rapid repression of quiescence-specific gene expression by epidermal growth factor, insulin, and pp60v-src

P A Bedard1, Y Yannoni, D L Simmons

  • 1Department of Cellular and Developmental Biology, Harvard University, Cambridge, Massachusetts 02138.

Insights

Researchers identified p20K, a novel secreted protein. Its production decreases with cell proliferation, suggesting a role in nonproliferating cells and potential regulation by mitogens.

Area of Science:

  • Molecular Biology
  • Cell Biology

Background:

  • Nonproliferating cells synthesize a specific secreted protein, p20K.
  • Mitogen stimulation leads to a rapid decrease in p20K levels.

Purpose of the Study:

  • To isolate and characterize the cDNA for the secreted protein p20K.
  • To investigate the regulation of p20K synthesis in response to mitogenic stimuli.

Main Methods:

  • cDNA isolation and sequencing.
  • Analysis of mRNA and protein expression levels.
  • Bioinformatic analysis for protein homology.

Main Results:

  • A cDNA for p20K was successfully isolated.
  • p20K mRNA and protein levels were found to decrease rapidly after mitogen treatment.
  • Sequence analysis predicted a novel protein with distant homology to alpha 2 mu-globulin and plasma retinol-binding protein.

Conclusions:

  • p20K is a novel secreted protein preferentially synthesized in nonproliferating cells.
  • p20K expression is downregulated by mitogenic signals.
  • The predicted protein structure suggests a potential functional relationship with other binding proteins.

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