Colony stimulating factor-1 (CSF-1) stimulates temperature dependent phosphorylation and activation of the RAF-1 proto-oncogene product

M. Baccarini, D. M. Sabatini, H. App, U. R. Rapp, E. R. Stanley

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Abstract

The serine/threonine kinase RAF-1 is phosphorylated in intact macrophages in response to CSF-1 at 37°C. The augmented phosphorylation of RAF-1 and a concomitant increase in RAF-1 associated serine/threonine kinase activity are kinetically later events than CSF-1 induced protein tyrosine phosphorylation. Furthermore, phospho-amino acid analysis of RAF-1 reveals the presence of phosphoserine, trace amounts of phosphothreonine but no phosphotyrosine and the phosphorylated RAF-1 does not react with anti-phosphotyrosine antibodies. In contrast to CSF-1 induced protein tyrosine phosphorylation, RAF-1 phosphorylation and activation are temperature dependent and do not occur at 4°C. Furthermore, coprecipitation experiments failed to reveal any noncovalent association of RAF-1 with the CSF-1 receptor. Thus, while RAF-1 is not a direct substrate for the CSF-1 receptor tyrosine kinase in vivo, its temperature dependent phosphorylation and activation represent an intriguing aspect of the CSF-1 response.

Original languageEnglish (US)
Pages (from-to)3649-3657
Number of pages9
JournalEMBO Journal
Volume9
Issue number11
Publication statusPublished - Oct 29 1990

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Keywords

  • CSF-1
  • PDGF
  • RAF-1 kinase
  • growth factor receptors
  • signal transduction

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

Cite this

Baccarini, M., Sabatini, D. M., App, H., Rapp, U. R., & Stanley, E. R. (1990). Colony stimulating factor-1 (CSF-1) stimulates temperature dependent phosphorylation and activation of the RAF-1 proto-oncogene product. EMBO Journal, 9(11), 3649-3657.