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Updated: May 7, 2026

Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development
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Bcl-2 targets the protein kinase Raf-1 to mitochondria

H G Wang1, U R Rapp, J C Reed

  • 1The Burnham Institute, Program on Apoptosis and Cell Death Research, La Jolla, California 92037, USA.

Cell
|November 15, 1996
PubMed

Insights

Bcl-2 protein targets Raf-1 kinase to mitochondria, preventing cell death by phosphorylating BAD. This mitochondrial localization is crucial for Bcl-2

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Bcl-2 is a key regulator of apoptosis.
  • Raf-1 is a kinase involved in cell signaling.
  • Mitochondria play a central role in programmed cell death.

Purpose of the Study:

  • To investigate if Bcl-2 can target Raf-1 kinase to mitochondria.
  • To determine the role of Raf-1 localization in apoptosis regulation.
  • To elucidate the mechanism by which Bcl-2 mediates apoptosis resistance.

Main Methods:

  • Utilized a green fluorescent protein (GFP)-Raf-1 fusion protein.
  • Engineered Raf-1 with outer mitochondrial membrane targeting sequences.
  • Assessed cellular protection from apoptosis.
  • Analyzed protein phosphorylation (BAD, ERK-1, ERK-2).

Main Results:

  • Bcl-2 targeted GFP-Raf-1 fusion protein to mitochondria.
  • Mitochondrial-targeted active Raf-1 protected cells from apoptosis.
  • Mitochondrial-targeted Raf-1 phosphorylated BAD.
  • Plasma membrane-targeted Raf-1 did not protect cells and phosphorylated ERK-1/ERK-2.
  • Untargeted active Raf-1 enhanced Bcl-2-mediated apoptosis resistance.
  • Kinase-inactive Raf-1 mutant abrogated Bcl-2's apoptosis suppression.

Conclusions:

  • Bcl-2 targets Raf-1 to mitochondrial membranes.
  • Mitochondrial Raf-1 phosphorylates BAD, contributing to apoptosis resistance.
  • Raf-1's kinase activity and mitochondrial localization are essential for Bcl-2's anti-apoptotic function.

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