Abstract
The product of the c-raf-1 proto-oncogene, Raf-1, is a 74,000-dalton cytoplasmic serine/threonine protein kinase that has been implicated as an intermediate in signal transduction mechanisms. In the human factor-dependent myeloid cell line MO7, both granulocyte-macrophage colony stimulating factor (GM-CSF) and Interleukin-3 (IL-3) were found to induce rapid, dose-dependent phosphorylation of Raf-1, which resulted in altered Raf-1 mobility in sodium dodecyl sulfate-polyacrylamide gels. The increase in phosphorylation was due primarily to an increase in phosphoserine, with only a minor component (<2%) of phosphotyrosine. PMA (12-phorbol 13-myristic acid) also induced Raf-1 phosphorylation in MO7 cells, but the resulting alteration in electrophoretic mobility was different than that observed after GM-CSF or IL-3. GM-CSF and IL-3 rapidly and transiently increased Raf-1 kinase activity using Histone H1 as a substrate in an imune complex kinase assay in vitro. These results suggest that phosphorylation of Raf-1 could play a role in some aspect of GM-CSF and IL-3 signal transduction.
Original language | English (US) |
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Pages (from-to) | 243-248 |
Number of pages | 6 |
Journal | Blood |
Volume | 77 |
Issue number | 2 |
DOIs | |
State | Published - 1991 |
Externally published | Yes |
ASJC Scopus subject areas
- Biochemistry
- Immunology
- Hematology
- Cell Biology