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Updated: Jul 13, 2026

Assessment of Submitochondrial Protein Localization in Budding Yeast Saccharomyces cerevisiae
Published on: July 19, 2021
The mitochondrial TOM complex is required for tBid/Bax-induced cytochrome c release
Martin Ott1, Erik Norberg, Katharina M Walter
1Institute of Environmental Medicine, Division of Toxicology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
Abstract:
Cytochrome c release from mitochondria is a key event in apoptosis signaling that is regulated by Bcl-2 family proteins. Cleavage of the BH3-only protein Bid by multiple proteases leads to the formation of truncated Bid (tBid), which, in turn, promotes the oligomerization/insertion of Bax into the mitochondrial outer membrane and the resultant release of proteins residing in the intermembrane space. Bax, a monomeric protein in the cytosol, is targeted by a yet unknown mechanism to the mitochondria. Several hypotheses have been put forward to explain this targeting specificity. Using mitochondria isolated from different mutants of the yeast Saccharomyces cerevisiae and recombinant proteins, we have now investigated components of the mitochondrial outer membrane that might be required for tBid/Bax-induced cytochrome c release. Here, we show that the protein translocase of the outer mitochondrial membrane is required for Bax insertion and cytochrome c release.
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