IndraLab
Statements
RAF1 is active.
36
38
|
"Protein phosphatase 5 (PP5) was identified as an inactivator that associates with Raf-1 on growth factor stimulation and selectively dephosphorylates an essential activating site, Ser 338. The PP5-mediated dephosphorylation of Ser 338 inhibited Raf-1 activity and downstream signalling to MEK"
"The first RAS effector pathway to be identified was the RAF-MEK-ERK pathway. This pathway is an essential, shared element of mitogenic signaling involving tyrosine kinase receptors, leading to a wide range of cellular responses, including growth, differentiation, inflammation, and apoptosis.23 The RAF family of proteins (Raf-1, A-Raf, and B-Raf) is serine/threonine kinases that bind to the effector region of RAS-GTP, thus inducing translocation of the protein to the plasma membrane."
"We have examined whether the other two members of the Raf family, A-Raf and B-Raf, are regulated in a similar way to Raf-1. A-Raf behaves like Raf-1, being weakly activated by oncogenic Ras more strongly activated by oncogenic Src, and these signals synergize to give maximal activation. B-Raf by contrast is strongly activated by oncogenic Ras alone and is not activated by oncogenic Src."
"Among other effectors, active ras binds and activates the raf kinase, iniziating a kinase cascade involving serine phosporylation of mek1/2 (mapkk) and tyrosine and threonine phosphorylation of erk1/2. the raf family of proteins (raf-1, a-raf, and b-raf) is serine/threonine kinases that bind to the effector region of ras-gtp, thus inducing translocation of the protein to the plasma membrane. Once there, raf proteins are activated and phosphorylated by different protein kinases.. Association of ras with the mapk kinase kinase, raf, initiates the raf mek erk map kinase cascade."
"Among other effectors, active ras binds and activates the raf kinase, iniziating a kinase cascade involving serine phosporylation of mek1/2 (mapkk) and tyrosine and threonine phosphorylation of erk1/2. the raf family of proteins (raf-1, a-raf, and b-raf) is serine/threonine kinases that bind to the effector region of ras-gtp, thus inducing translocation of the protein to the plasma membrane. Once there, raf proteins are activated and phosphorylated by different protein kinases.. Association of ras with the mapk kinase kinase, raf, initiates the raf mek erk map kinase cascade."
"Erk-induced raf-1 phosphorylation sustains raf-1 kinase activity furthermore, using direct in vitro phosphorylation we show that these sites are direct targets of erk-1 and using phosphospecific antibodies developed against one of the sites, s296, show that these sites are physiological phosphorylation sites induced in vivo after mitogen stimulation."
"Erk-induced raf-1 phosphorylation sustains raf-1 kinase activity furthermore, using direct in vitro phosphorylation we show that these sites are direct targets of erk-1 and using phosphospecific antibodies developed against one of the sites, s296, show that these sites are physiological phosphorylation sites induced in vivo after mitogen stimulation."
"P21-activated kinase 1 (pak1)-dependent phosphorylation of raf-1 regulates its mitochondrial localization, phosphorylation of bad, and bcl-2 association. moreover, the mitochondrial translocation of raf-1 and the interaction between raf-1 and bcl-2 are regulated by raf-1 phosphorylation at ser-338/ser-339."
"We show cnk2 interacts with raf. cnk2 interacts with the gef domain of rlf and with both the regulatory and catalytic domains of raf. The raf interaction was also mapped to the carboxyl-terminal half of cnk2. Overexpression of cnk2 results in inhibition of the mapk signaling pathway."
RAF1 is inactive.
4
33
|
"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"
"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"
"Here, we identify six residues of Raf-1 (S29, S43, S289, S296, S301, and S642) that become hyperphosphorylated in a manner coincident with Raf-1 inactivation. | Five of the identified sites are proline-directed targets of activated ERK, and phosphorylation of all six sites requires MEK signaling, indicating a negative feedback mechanism. Hyperphosphorylation of these six sites inhibits the Ras/Raf-1 interaction and desensitizes Raf-1 to additional stimuli.|FLAG-Raf-1 phosphorylated by activated ERK2"
"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."
"Here, we identify six residues of Raf-1 (S29, S43, S289, S296, S301, and S642) that become hyperphosphorylated in a manner coincident with Raf-1 inactivation. | Five of the identified sites are proline-directed targets of activated ERK, and phosphorylation of all six sites requires MEK signaling, indicating a negative feedback mechanism. Hyperphosphorylation of these six sites inhibits the Ras/Raf-1 interaction and desensitizes Raf-1 to additional stimuli.|FLAG-Raf-1 phosphorylated by activated ERK2"
"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."
"Here, we identify six residues of Raf-1 (S29, S43, S289, S296, S301, and S642) that become hyperphosphorylated in a manner coincident with Raf-1 inactivation. | Five of the identified sites are proline-directed targets of activated ERK, and phosphorylation of all six sites requires MEK signaling, indicating a negative feedback mechanism. Hyperphosphorylation of these six sites inhibits the Ras/Raf-1 interaction and desensitizes Raf-1 to additional stimuli.|FLAG-Raf-1 phosphorylated by activated ERK2"
"Here, we identify six residues of Raf-1 (S29, S43, S289, S296, S301, and S642) that become hyperphosphorylated in a manner coincident with Raf-1 inactivation. | Five of the identified sites are proline-directed targets of activated ERK, and phosphorylation of all six sites requires MEK signaling, indicating a negative feedback mechanism. Hyperphosphorylation of these six sites inhibits the Ras/Raf-1 interaction and desensitizes Raf-1 to additional stimuli.|FLAG-Raf-1 phosphorylated by activated ERK2"
"Here, we identify six residues of Raf-1 (S29, S43, S289, S296, S301, and S642) that become hyperphosphorylated in a manner coincident with Raf-1 inactivation. | Five of the identified sites are proline-directed targets of activated ERK, and phosphorylation of all six sites requires MEK signaling, indicating a negative feedback mechanism. Hyperphosphorylation of these six sites inhibits the Ras/Raf-1 interaction and desensitizes Raf-1 to additional stimuli.|FLAG-Raf-1 phosphorylated by activated ERK2"
"Here, we identify six residues of Raf-1 (S29, S43, S289, S296, S301, and S642) that become hyperphosphorylated in a manner coincident with Raf-1 inactivation. | Five of the identified sites are proline-directed targets of activated ERK, and phosphorylation of all six sites requires MEK signaling, indicating a negative feedback mechanism. Hyperphosphorylation of these six sites inhibits the Ras/Raf-1 interaction and desensitizes Raf-1 to additional stimuli.|FLAG-Raf-1 phosphorylated by activated ERK2"
"Here we show that mammalian Sprouty4 suppresses vascular epithelial growth factor (VEGF)-induced, Ras-independent activation of Raf1 but does not affect epidermal growth factor (EGF)-induced, Ras-dependent activation of Raf1. Sprouty4 binds to Raf1 through its carboxy-terminal cysteine-rich domain, and this binding is necessary for the inhibitory activity of Sprouty4."
RAF1 is kinase-active.
6
8
|
"bFGF activated Raf-1 via p21-activated protein kinase-1 (PAK-1) phosphorylation of serines 338 and 339, resulting in Raf-1 mitochondrial translocation and endothelial cell protection from the intrinsic pathway of apoptosis, independent of the mitogen-activated protein kinase kinase-1 (MEK1)"
"bFGF activated Raf-1 via p21-activated protein kinase-1 (PAK-1) phosphorylation of serines 338 and 339, resulting in Raf-1 mitochondrial translocation and endothelial cell protection from the intrinsic pathway of apoptosis, independent of the mitogen-activated protein kinase kinase-1 (MEK1)"
"bFGF activated Raf-1 via p21-activated protein kinase-1 (PAK-1) phosphorylation of serines 338 and 339, resulting in Raf-1 mitochondrial translocation and endothelial cell protection from the intrinsic pathway of apoptosis, independent of the mitogen-activated protein kinase kinase-1 (MEK1)"
RAF1 is kinase-inactive.
7
7
|
"Phosphorylation. Raf is principally activated by phosphorylation of specific amino acid residues as shown for each isoform in Figure 4. From an evolutionary standpoint, the Raf activation sites are highly conserved from yeast to humans. Several amino acids in Raf, particularly serine (S) 259 and S621, which bind 14-3-3 and maintain C-Raf in a closed auto-inhibited conformation, are phosphorylated in the basal state."