Abstract
Raf-1 serine- and threonine-specific protein kinase is transiently activated in cells expressing the epidermal growth factor (EGF) receptor upon treatment with EGF. The stimulated EGF receptor coimmunoprecipitates with Raf-1 kinase and mediates protein kinase C-independent phosphorylation of Raf-1 on serine residues. Hyperphosphorylated Raf-1 has lower mobility on sodium dodecyl sulfate gels and has sixfold-increased activity in immunocomplex kinase assays with histone H1 or a Raf-1 sequence-derived peptide as a substrate. Raf-1 activation requires kinase-active EGF receptor; a point mutant lacking tyrosine kinase activity is inactive in Raf-1 coupling and association. It is noteworthy that tyrosine phosphorylation of c-Raf-1 induced by EGF was not detected in these cells. These observations suggest that Raf-1 kinase may act as an important downstream effector of EGF signal transduction.
Original language | English (US) |
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Pages (from-to) | 913-919 |
Number of pages | 7 |
Journal | Molecular and cellular biology |
Volume | 11 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1991 |
Externally published | Yes |
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology