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Updated: Oct 8, 2026

Examining BCL-2 Family Function with Large Unilamellar Vesicles
08:35

Examining BCL-2 Family Function with Large Unilamellar Vesicles

Published on: October 5, 2012

Failure of Bcl-2 family members to interact with Apaf-1 in normal and apoptotic cells

S Conus1, T Rossé, C Borner

  • 1Institute of Biochemistry, University of Fribourg, Rue du Musée 5, CH-1700 Fribourg, Switzerland.

Cell Death and Differentiation
|March 30, 2001
PubMed

Insights

Mammalian Bcl-2 proteins, like C. elegans CED-9, regulate apoptosis. This study found that Bcl-2, Bcl-xL, and Bax do not directly bind to Apaf-1, suggesting Apaf-1 is not a direct target.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • CED-9 inhibits apoptosis in C. elegans by binding CED-4, preventing CED-3 activation.
  • Mammalian homologs Bcl-2 and Bcl-xL also inhibit apoptosis, but their interaction with Apaf-1 (a CED-4 homolog) is debated.

Purpose of the Study:

  • To investigate the interaction between Apaf-1 and Bcl-2 family members (Bcl-2, Bcl-xL, Bax) within cells.
  • To resolve conflicting previous findings regarding Bcl-xL and Apaf-1 interactions.

Main Methods:

  • Immunofluorescence microscopy to determine protein localization.
  • Western blot analysis to detect protein interactions.
  • Co-expression of proteins in cells to mimic physiological conditions.

Main Results:

  • Apaf-1 is primarily cytoplasmic, while Bcl-2, Bcl-xL, and Bax localize to nuclear/ER and mitochondrial membranes.
  • Protein localization patterns remained distinct upon co-expression, indicating no significant sequestration of cytoplasmic Apaf-1.
  • Immunoprecipitation confirmed no interaction between Apaf-1 and Bcl-2 or Bcl-xL.

Conclusions:

  • Apaf-1 does not appear to directly interact with Bcl-2, Bcl-xL, or Bax.
  • The mechanism by which Bcl-2 family proteins regulate apoptosis may not involve direct binding to Apaf-1.

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