Role for Bcl-xL as an inhibitor of cytosolic cytochrome C accumulation in DNA damage-induced apoptosis.

Cytochrome C is a mitochondrial protein that induces apoptosis when released into the cytosol or when added to cell-free extracts. Here we show that cells that overexpress the Bcl-2-related protein Bcl-xL fail to accumulate cytosolic cytochrome C or undergo apoptosis in response to genotoxic stress. Coimmunoprecipitation studies demonstrate that Bcl-xL ...
associates with cytochrome C. Cytochrome C binds directly and specifically to Bcl-xL and not to the proapoptotic Bcl-xs protein. The results also demonstrate that Bcl-xs blocks binding of cytochrome C to Bcl-xL. Our findings support a role for Bcl-xL in protecting cells from apoptosis by inhibiting the availability of cytochrome C in the cytosol.
Mesh Terms:
Apoptosis, Cytochrome c Group, Cytosol, DNA Damage, Gene Expression Regulation, Neoplastic, Humans, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-bcl-2, Tumor Cells, Cultured, bcl-X Protein
Proc. Natl. Acad. Sci. U.S.A.
Date: Jun. 24, 1997
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