• Register
X
Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

X

Leaving Community

Are you sure you want to leave this community? Leaving the community will revoke any permissions you have been granted in this community.

No
Yes

Negative regulation of the serine/threonine kinase B-Raf by Akt.

B-Raf contains multiple Akt consensus sites located within its amino-terminal regulatory domain. One site, Ser(364), is conserved with c-Raf but two additional sites, Ser(428) and Thr(439), are unique to B-Raf. We have investigated the role of both the conserved and unique phosphorylation sites in the regulation of B-Raf activity in vitro and in vivo. We show that phosphorylation of B-Raf by Akt occurs at multiple residues within its amino-terminal regulatory domain, at both the conserved and unique phosphorylation sites. The alteration of the serine residues within the Akt consensus sites to alanines results in a progressive increase in enzymatic activity in vitro and in vivo. Furthermore, expression of Akt inhibits epidermal growth factor-induced B-Raf activity and inhibition of Akt with LY294002 up-regulates B-Raf activity, suggesting that Akt negatively regulates B-Raf in vivo. Our results demonstrate that B-Raf activity can be negatively regulated by Akt through phosphorylation in the amino-terminal regulatory domain of B-Raf. This cross-talk between the B-Raf and Akt serine/threonine kinases is likely to play an important role in modulating the signaling specificity of the Ras/Raf pathway and in promoting biological outcome.

Pubmed ID: 10869359

Authors

  • Guan KL
  • Figueroa C
  • Brtva TR
  • Zhu T
  • Taylor J
  • Barber TD
  • Vojtek AB

Journal

The Journal of biological chemistry

Publication Data

September 1, 2000

Associated Grants

  • Agency: NIGMS NIH HHS, Id: GM51586

Mesh Terms

  • Amino Acid Sequence
  • Cell Line
  • Consensus Sequence
  • Enzyme Activation
  • Humans
  • Mutagenesis, Site-Directed
  • Phosphorylation
  • Precipitin Tests
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-akt
  • Proto-Oncogene Proteins c-raf