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

Manuela Baccarini, David M. Sabatini, Harald App, Ulf R. Rapp, E. Richard Stanley

Research output: Contribution to journalArticlepeer-review

121 Scopus citations

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, phosphoamino 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 non-covalent 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
StatePublished - 1990

Keywords

  • CSF-1
  • Growth factor receptors
  • PDGF
  • RAF-1 kinase
  • Signal transduction

ASJC Scopus subject areas

  • General Immunology and Microbiology
  • General Biochemistry, Genetics and Molecular Biology
  • Molecular Biology
  • General Neuroscience

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