Related Experiment Video

Updated: Jul 20, 2026

Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development
09:32

Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development

Published on: June 15, 2017

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

K L Guan1, C Figueroa, T R Brtva

  • 1Department of Biological Chemistry and the Institute of Gerontology, University of Michigan, Ann Arbor, Michigan 48109, USA.

The Journal of Biological Chemistry
|June 28, 2000
PubMed

Insights

Akt negatively regulates B-Raf kinase activity through phosphorylation at specific sites within its regulatory domain. This cross-talk impacts the Ras/Raf signaling pathway and cellular outcomes.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Biochemistry

Background:

  • B-Raf and Akt are key kinases in cellular signaling pathways.
  • B-Raf possesses unique and conserved Akt phosphorylation sites in its regulatory domain.
  • Understanding kinase cross-talk is crucial for deciphering signaling specificity.

Purpose of the Study:

  • To investigate the role of B-Raf phosphorylation sites in Akt-mediated regulation.
  • To elucidate the in vitro and in vivo effects of Akt on B-Raf activity.
  • To determine the impact of this cross-talk on the Ras/Raf pathway.

Main Methods:

  • In vitro kinase assays to assess B-Raf enzymatic activity.
  • In vivo studies involving Akt expression and inhibition (LY294002).
  • Site-directed mutagenesis of B-Raf phosphorylation sites (Ser to Ala).

Main Results:

  • Akt phosphorylates B-Raf at multiple residues, including conserved and unique sites.
  • Mutating Akt consensus sites on B-Raf progressively increases its enzymatic activity.
  • Akt expression inhibits EGF-induced B-Raf activity, while LY294002 up-regulates it.

Conclusions:

  • Akt negatively regulates B-Raf activity via phosphorylation in its amino-terminal domain.
  • This cross-talk modulates Ras/Raf pathway signaling specificity.
  • The findings highlight a significant regulatory mechanism influencing biological outcomes.

More Related Videos

Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods07:49

Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods

Published on: July 17, 2019

Bioluminescence Resonance Energy Transfer (BRET)-Based Assay for Measuring Interactions of CRAF with 14-3-3 Proteins in Live Cells06:44

Bioluminescence Resonance Energy Transfer (BRET)-Based Assay for Measuring Interactions of CRAF with 14-3-3 Proteins in Live Cells

Published on: March 1, 2024

Related Concept Videos

The Ras Gene02:38

The Ras Gene

The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...
mTOR Signaling and Cancer Progression03:03

mTOR Signaling and Cancer Progression

The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...
Amplifying Signals via Enzymatic Cascade01:22

Amplifying Signals via Enzymatic Cascade

When a ligand binds to a cell-surface receptor, the receptor's intracellular domain changes shape, which may either activate its enzyme function or allow its binding to other molecules. The initial signal is amplified by most signal transduction pathways. This means that a single ligand molecule can activate multiple molecules of a downstream target. Proteins that relay a signal are most commonly phosphorylated at one or more sites, activating or inactivating the protein. Kinases catalyze the...
MAPK Signaling Cascades01:07

MAPK Signaling Cascades

Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
The JAK-STAT Signaling Pathway01:20

The JAK-STAT Signaling Pathway

Several cytokine receptors have tightly bound Janus kinase or JAK proteins attached at their cytosolic tail. Small signaling molecules such as cytokines, growth hormones, or prolactins bind to the cytokine receptors and initiate their dimerization. The dimerization brings the cytosolic JAKs together that trans-phosphorylate and activates each other. The activated JAKs now phosphorylate cytosolic tails of the cytokine receptors, which serve as binding sites for adaptor proteins such as  SH2...
PI3K/mTOR/AKT Signaling Pathway01:22

PI3K/mTOR/AKT Signaling Pathway

The mammalian target of rapamycin  (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1  (mTORC1) and mTOR complex 2  (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast,  mTORC2 consists of a rapamycin-insensitive companion...