Regulation of a ribosomal protein S6 kinase activity by the Rous sarcoma virus transforming protein, serum, or phorbol ester Academic Article uri icon


MeSH Major

  • Growth Substances
  • Phorbols
  • Protein Kinases
  • Retroviridae Proteins
  • Ribosomal Proteins
  • Tetradecanoylphorbol Acetate


  • Protein kinase capable of phosphorylating 40S ribosomal protein S6 on serine residues has been detected in chicken embryo fibroblasts. This activity appears to be regulated in direct response to expression of pp60v-src in chicken embryo fibroblasts infected with a temperature-sensitive transformation mutant of Rous sarcoma virus. Partially purified S6 kinase was highly specific for S6 in 40S ribosomal subunits. The S6 kinase was not inhibited by calcium or by the heat-stable inhibitor of cAMP-dependent protein kinase, nor was it activated by phosphatidylserine, diacylglycerol, and calcium. Thus, it is distinct from protein kinase C and cAMP-dependent protein kinase, which are capable of phosphorylating S6 in vitro. The tumor-promoter phorbol 12-myristate 13-acetate also stimulated ribosomal protein S6 kinase activity in serum-starved chicken embryo fibroblasts, whereas phorbol, the inactive analog of phorbol 12-myristate 13-acetate, had no effect. S6 kinase activity stimulated by expression of pp60v-src, by phorbol 12-myristate 13-acetate, or by serum growth factors exhibited similar chromatographic properties upon ion-exchange chromatography. These results suggest that a common protein kinase may be activated by three diverse stimuli all involved in regulating cell proliferation.

publication date

  • December 1985



  • Academic Article



  • eng

PubMed Central ID

  • PMC391385

PubMed ID

  • 3934663

Additional Document Info

start page

  • 7621

end page

  • 5


  • 82


  • 22