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Bcl-2 associates with the ras-related protein R-ras p23
M J Fernandez-Sarabia1, J R Bischoff
1ONYX Pharmaceuticals, Richmond, California 94806.
Abstract:
Apoptosis is an important but poorly understood mechanism of cell regulation. Growth factor deprivation can trigger apoptosis in a variety of cells, suggesting the existence of a signal transduction pathway responding to external signals and leading to apoptosis. Overexpression of the proto-oncogene bcl-2 can override these signals and block apoptosis, indicating that the bcl-2 protein (Bcl-2) is an important component of the apoptotic response. The identification of Bcl-2-binding proteins might help explain how Bcl-2 acts to regulate apoptosis. Here we use the yeast two-hybrid system to show that the human ras-related protein R-ras p23 (ref 16-18) binds to Bcl-2. This association is also detected in immunoprecipitates from human cell extracts. The association requires full-length Bcl-2 but the C-terminal 60 amino acids of R-ras p23 are sufficient for the interaction. These results provide evidence of a putative component of a signal transduction pathway involved in the regulation of apoptosis.
Insights
Scientists discovered that the R-ras p23 protein binds to Bcl-2, a key regulator of apoptosis (programmed cell death). This finding helps explain how Bcl-2 functions in cell death signaling pathways.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Apoptosis, or programmed cell death, is a critical cellular process that remains incompletely understood.
- Growth factor deprivation can initiate apoptosis, suggesting a role for external signals and signal transduction pathways.
- The proto-oncogene bcl-2 protein (Bcl-2) is a crucial regulator that can inhibit apoptosis.
Purpose of the Study:
- To identify proteins that interact with Bcl-2.
- To elucidate the molecular mechanisms by which Bcl-2 regulates apoptosis.
- To investigate potential components of the apoptotic signal transduction pathway.
Main Methods:
- Yeast two-hybrid system for protein-protein interaction screening.
- Co-immunoprecipitation assays using human cell extracts.
- Analysis of protein domains required for interaction.
Main Results:
- The human ras-related protein R-ras p23 was identified as a Bcl-2-binding protein using the yeast two-hybrid system.
- The interaction between R-ras p23 and Bcl-2 was confirmed in human cell extracts via immunoprecipitation.
- Full-length Bcl-2 is required for the interaction, while the C-terminal 60 amino acids of R-ras p23 are sufficient.
Conclusions:
- R-ras p23 is a novel Bcl-2-binding protein.
- This interaction suggests R-ras p23 is a potential component of the signal transduction pathway regulating apoptosis.
- The findings provide new insights into the molecular mechanisms of apoptosis regulation by Bcl-2.