Interleukin-3 and granulocyte-macrophage colony-stimulating factor mediate rapid phosphorylation and activation of cytosolic c-raf.
Interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor induce the rapid phosphorylation of the c-raf protein in the growth factor-dependent FDC-P1 and DA-3 murine myeloid cell lines. Furthermore, immunoprecipitates of c-raf isolated from growth factor-stimulated cells demonstrate a marked increase in intrinsic protein kinase activity as measured in vitro. IL-3 and granulocyte-macrophage colony-stimulating factor induce phosphorylation of c-raf at both serine and tyrosine residues. Antiphosphotyrosine immunoprecipitates from IL-3-stimulated cells demonstrate the rapid and coordinate phosphorylation of both c-raf and a protein co-migrating with the 140-kDa putative IL-3 receptor component. Collectively, the findings of rapid and coordinate ligand-induced phosphorylation of a potential IL-3 growth factor receptor component and cytoplasmic c-raf with concomitant c-raf activation provide a cogent sequential molecular model for linking external growth stimuli to intracellular signal transduction events.
John Hopkins Oncology Center, Baltimore, Maryland 21231.
M P
MP
Carroll
I
I
Clark-Lewis
U R
UR
Rapp
W S
WS
May
D000818:Animals; D002460:Cell Line; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D007163:Immunosorbent Techniques; D007377:Interleukin-3 / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D008970:Molecular Weight; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D019000:Phosphotyrosine; D011494:Protein Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D007377:Interleukin-3; D011518:Proto-Oncogene Proteins; D010768:Phosphoserine; D019000:Phosphotyrosine; D014443:Tyrosine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011494:Protein Kinases; D019908:Proto-Oncogene Proteins c-raf