The cytoplasmic Raf-1 kinase is essential for mitogenic signalling
by growth factors, which couple to tyrosine kinases, and by tumor-promoting
phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate, which
activate protein kinase C (PKC). Signalling by the Raf-1 kinase can
be blocked by activation of the cyclic AMP (cAMP)-dependent protein
kinase A (PKA). The molecular mechanism of this inhibition is not
precisely known but has been suggested to involve attenuation of
Raf-1 binding to Ras. Using purified proteins, we show that in addition
to weakening the interaction of Raf-1 with Ras, PKA can inhibit Raf-1
function directly via phosphorylation of the Raf-1 kinase domain.
Phosphorylation by PKA interferes with the activation of Raf-1 by
either PKC alpha or the tyrosine kinase Lck and even can downregulate
the kinase activity of Raf-1 previously activated by PKC alpha or
amino-terminal truncation. This type of inhibition can be dissociated
from the ability of Raf-1 to associate with Ras, since (i) the isolated
Raf-1 kinase domain, which lacks the Ras binding domain, is still
susceptible to inhibition by PKA, (ii) phosphorylation of Raf-1 by
PKC alpha alleviates the PKA-induced reduction of Ras binding but
does not prevent the downregulation of Raf-1 kinase activity by PKA
and (iii) cAMP agonists antagonize transformation by v-Raf, which
is Ras independent.
Hafner, S Adler, H S Mischak, H Janosch, P Heidecker, G Wolfman,
A Pippig, S Lohse, M Ueffing, M Kolch, W United states Molecular
and cellular biology Mol Cell Biol. 1994 Oct;14(10):6696-703.
%0 Journal Article
%1 Hafner1994
%A Hafner, S.
%A Adler, H. S.
%A Mischak, H.
%A Janosch, P.
%A Heidecker, G.
%A Wolfman, A.
%A Pippig, S.
%A Lohse, M.
%A Ueffing, M.
%A Kolch, W.
%D 1994
%J Mol Cell Biol
%K *MAP 1 3T3 AMP-Dependent Activation Animals Binding C-alpha C/metabolism Cell Cyclic Enzyme Isoenzymes/metabolism Kinase Kinases/*metabolism Kinases/metabolism Lymphocyte Mice Neoplastic Oncogene Oncogenic/metabolism Phosphorylation Protein Protein-Serine-Threonine Protein-Tyrosine Proteins Proteins, Proto-Oncogene Retroviridae Specific Specificity Substrate Transformation, Tyrosine c-raf p21(ras)/metabolism p56(lck) v-raf Proteins/metabolism
%N 10
%P 6696-703
%T Mechanism of inhibition of Raf-1 by protein kinase A
%U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=7935389
%V 14
%X The cytoplasmic Raf-1 kinase is essential for mitogenic signalling
by growth factors, which couple to tyrosine kinases, and by tumor-promoting
phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate, which
activate protein kinase C (PKC). Signalling by the Raf-1 kinase can
be blocked by activation of the cyclic AMP (cAMP)-dependent protein
kinase A (PKA). The molecular mechanism of this inhibition is not
precisely known but has been suggested to involve attenuation of
Raf-1 binding to Ras. Using purified proteins, we show that in addition
to weakening the interaction of Raf-1 with Ras, PKA can inhibit Raf-1
function directly via phosphorylation of the Raf-1 kinase domain.
Phosphorylation by PKA interferes with the activation of Raf-1 by
either PKC alpha or the tyrosine kinase Lck and even can downregulate
the kinase activity of Raf-1 previously activated by PKC alpha or
amino-terminal truncation. This type of inhibition can be dissociated
from the ability of Raf-1 to associate with Ras, since (i) the isolated
Raf-1 kinase domain, which lacks the Ras binding domain, is still
susceptible to inhibition by PKA, (ii) phosphorylation of Raf-1 by
PKC alpha alleviates the PKA-induced reduction of Ras binding but
does not prevent the downregulation of Raf-1 kinase activity by PKA
and (iii) cAMP agonists antagonize transformation by v-Raf, which
is Ras independent.
@article{Hafner1994,
abstract = {The cytoplasmic Raf-1 kinase is essential for mitogenic signalling
by growth factors, which couple to tyrosine kinases, and by tumor-promoting
phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate, which
activate protein kinase C (PKC). Signalling by the Raf-1 kinase can
be blocked by activation of the cyclic AMP (cAMP)-dependent protein
kinase A (PKA). The molecular mechanism of this inhibition is not
precisely known but has been suggested to involve attenuation of
Raf-1 binding to Ras. Using purified proteins, we show that in addition
to weakening the interaction of Raf-1 with Ras, PKA can inhibit Raf-1
function directly via phosphorylation of the Raf-1 kinase domain.
Phosphorylation by PKA interferes with the activation of Raf-1 by
either PKC alpha or the tyrosine kinase Lck and even can downregulate
the kinase activity of Raf-1 previously activated by PKC alpha or
amino-terminal truncation. This type of inhibition can be dissociated
from the ability of Raf-1 to associate with Ras, since (i) the isolated
Raf-1 kinase domain, which lacks the Ras binding domain, is still
susceptible to inhibition by PKA, (ii) phosphorylation of Raf-1 by
PKC alpha alleviates the PKA-induced reduction of Ras binding but
does not prevent the downregulation of Raf-1 kinase activity by PKA
and (iii) cAMP agonists antagonize transformation by v-Raf, which
is Ras independent.},
added-at = {2010-12-14T18:12:02.000+0100},
author = {Hafner, S. and Adler, H. S. and Mischak, H. and Janosch, P. and Heidecker, G. and Wolfman, A. and Pippig, S. and Lohse, M. and Ueffing, M. and Kolch, W.},
biburl = {https://www.bibsonomy.org/bibtex/23b58951152f00b33f213c30ad5709716/pharmawuerz},
endnotereftype = {Journal Article},
interhash = {f940b69187a015fdff26465ff9fb66ac},
intrahash = {3b58951152f00b33f213c30ad5709716},
issn = {0270-7306 (Print) 0270-7306 (Linking)},
journal = {Mol Cell Biol},
keywords = {*MAP 1 3T3 AMP-Dependent Activation Animals Binding C-alpha C/metabolism Cell Cyclic Enzyme Isoenzymes/metabolism Kinase Kinases/*metabolism Kinases/metabolism Lymphocyte Mice Neoplastic Oncogene Oncogenic/metabolism Phosphorylation Protein Protein-Serine-Threonine Protein-Tyrosine Proteins Proteins, Proto-Oncogene Retroviridae Specific Specificity Substrate Transformation, Tyrosine c-raf p21(ras)/metabolism p56(lck) v-raf Proteins/metabolism},
month = Oct,
note = {Hafner, S Adler, H S Mischak, H Janosch, P Heidecker, G Wolfman,
A Pippig, S Lohse, M Ueffing, M Kolch, W United states Molecular
and cellular biology Mol Cell Biol. 1994 Oct;14(10):6696-703.},
number = 10,
pages = {6696-703},
shorttitle = {Mechanism of inhibition of Raf-1 by protein kinase A},
timestamp = {2010-12-14T18:21:42.000+0100},
title = {Mechanism of inhibition of Raf-1 by protein kinase A},
url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=7935389},
volume = 14,
year = 1994
}