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Updated: Aug 15, 2026
10:50
Using In Vitro Fluorescence Resonance Energy Transfer to Study the Dynamics Of Protein Complexes at a Millisecond Time Scale
Published on: March 14, 2019
CED-4 forms a 2 : 2 heterotetrameric complex with CED-9 until specifically displaced by EGL-1 or CED-13
W D Fairlie1, M A Perugini, M Kvansakul
1The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia. fairlie@wehi.edu.au
Cell Death and Differentiation
|September 17, 2005
Summary
Researchers purified a stable CED-4/CED-9 complex, revealing how worm BH3-only proteins trigger apoptosis by dissociating CED-4 from CED-9, a mechanism not mimicked by mammalian proteins.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Biology
Background:
- The apoptosis pathway in Caenorhabditis elegans involves EGL-1 binding to CED-9, releasing CED-4 to activate caspase CED-3.
- The biophysical characteristics of the CED-4/CED-9 complex remain incompletely understood.
Purpose of the Study:
- To characterize the biophysical features of the CED-4/CED-9 complex.
- To investigate the mechanism of CED-4 dissociation from CED-9 by BH3-only proteins.
Main Methods:
- Coexpression of recombinant CED-4 and CED-9 in bacteria.
- Purification of a soluble and stable 2:2 heterotetrameric CED-4/CED-9 complex.
- Assay of synthetic BH3 domain peptides for their ability to dissociate the complex.
Main Results:
- A soluble, stable 2:2 heterotetrameric CED-4/CED-9 complex was successfully purified.
- Worm BH3-only protein peptides (EGL-1, CED-13) dissociated CED-4 from CED-9.
- Dissociation was specific, as mammalian BH3-only proteins could not displace CED-4, and a CED-9 gain-of-function mutant (G169E) resisted dissociation.
Conclusions:
- The study reports the first purification of a stable CED-4/CED-9 complex, providing insights into apoptosis regulation.
- Worm BH3-only proteins specifically disrupt the CED-4/CED-9 interaction, initiating the cell death cascade.
- This mechanism highlights species-specific differences in apoptosis regulation between worms and mammals.
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