IndraLab
Statements
"Akt (protein kinase b), a member of a different signaling pathway that also regulates these responses, interacted with raf and phosphorylated this protein at a highly conserved serine residue in its regulatory domain in vivo. This phosphorylation of raf by akt inhibited activation of the raf-mek-erk signaling pathway and shifted the cellular response in a human breast cancer cell line from cell cycle arrest to proliferation."
"Mapkerk1/2 is also able to phopshorylate the egf receptor, the ras exchange factor sos, mkkkraf1, and mkkmek1. The phosphorylation of each of these proteins by mapkerk1/2 is believed to reduce their catalytic activity. previous studies have shown that phosphorylation is required for raf-1 activation, and here, we identify six phosphorylation sites that contribute to the downregulation of raf-1 after mitogen stimulation. Five of the identified sites are proline-directed targets of activated erk"
"Using mass spectrometry, we identified raf-1 phosphorylation on three sp motif sites: s289/s296/s301. These sites were phosphorylated by extracellular signal-regulated kinase (erk)-1 in vitro, and their phosphorylation in vivo was dependent on endogenous erk activity. Functionally, erk-1 expression sustains raf-1 activation in a manner dependent on raf-1 phosphorylation on the identified sites, and s289/296/301a substitution markedly decreases the in vivo activity of raf-1 s259a."
"Mapkerk1/2 is also able to phopshorylate the egf receptor, the ras exchange factor sos, mkkkraf1, and mkkmek1. The phosphorylation of each of these proteins by mapkerk1/2 is believed to reduce their catalytic activity. previous studies have shown that phosphorylation is required for raf-1 activation, and here, we identify six phosphorylation sites that contribute to the downregulation of raf-1 after mitogen stimulation. Five of the identified sites are proline-directed targets of activated erk"