Related Experiment Video

Updated: Aug 10, 2026

Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods
07:49

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

Published on: July 17, 2019

Phosphatidylinositol-3-OH kinase as a direct target of Ras

P Rodriguez-Viciana1, P H Warne, R Dhand

  • 1Imperial Cancer Research Fund, London, UK.

Nature
|August 18, 1994
PubMed

Insights

Ras proteins directly bind to phosphatidylinositol-3-OH kinase, regulating its activity. This interaction influences cell signaling pathways, impacting cell growth and lipid production.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Biochemistry

Background:

  • Ras proteins (p21ras) are key regulators of cellular signaling pathways.
  • Phosphatidylinositol-3-OH kinase (PI3K) is involved in crucial cellular processes like growth and survival.
  • The precise interaction and regulatory role of Ras on PI3K activity were not fully elucidated.

Purpose of the Study:

  • To investigate the direct interaction between Ras and the catalytic subunit of PI3K.
  • To determine the functional consequences of Ras-PI3K interaction on phosphoinositide production.
  • To elucidate the role of Ras in regulating PI3K activity within cellular signaling.

Main Methods:

  • In vitro assays to assess GTP-dependent interaction between Ras and PI3K catalytic subunit.
  • In vivo studies using dominant-negative Ras mutant N17 in PC12 cells.
  • Transfection experiments with Ras and Raf in COS cells to measure lipid levels.

Main Results:

  • Ras (p21ras) directly binds to the PI3K catalytic subunit in a GTP-dependent manner via the Ras effector site.
  • Dominant-negative Ras mutant N17 inhibited growth factor-induced 3' phosphorylated phosphoinositide production in PC12 cells.
  • Ras transfection, but not Raf, significantly elevated 3' phosphorylated phosphoinositides in COS cells.

Conclusions:

  • Ras directly regulates phosphatidylinositol-3-OH kinase activity.
  • This interaction represents a critical point of divergence in signaling pathways downstream of Ras.
  • Ras-mediated PI3K regulation impacts cellular lipid metabolism and signaling.

More Related Videos

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry08:07

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry

Published on: July 26, 2019

Assessing Cellular Target Engagement by SHP2 (PTPN11) Phosphatase Inhibitors08:45

Assessing Cellular Target Engagement by SHP2 (PTPN11) Phosphatase Inhibitors

Published on: July 17, 2020

Related Concept Videos

Phosphoinositides and PIPs01:42

Phosphoinositides and PIPs

Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
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...
Small GTPases - Ras and Rho01:24

Small GTPases - Ras and Rho

Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
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...