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A novel GTPase-activating protein for R-Ras
T Yamamoto1, T Matsui, M Nakafuku
1Division of Signal Transduction, Nara Institute of Science and Technology, Ikoma, Japan.
The Journal of Biological Chemistry
|December 22, 1995
Summary
Researchers identified a novel GTPase-activating protein (GAP) for R-Ras, a key regulator in cell functions. This R-Ras GAP protein specifically binds to GTP-bound R-Ras, highlighting its role in cellular signaling pathways.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- R-Ras is a small GTP-binding protein involved in regulating gene expression, cell proliferation, and apoptosis.
- Understanding R-Ras regulation is crucial for deciphering its role in various cellular processes.
Purpose of the Study:
- To identify and characterize novel proteins that interact with R-Ras.
- To determine the function of an isolated R-Ras-interacting protein.
Main Methods:
- Affinity chromatography using glutathione S-transferase (GST)-R-Ras.
- GTP binding assays with various Ras proteins and GTP analogs.
- cDNA sequencing and recombinant protein expression.
- GTPase activity assays.
Main Results:
- An approximately 98 kDa protein (p98) was purified from bovine brain cytosol.
- p98 specifically bound to GTPγS-bound R-Ras, but not GDP-bound R-Ras or other Ras family members.
- The cDNA sequence predicted an 834-amino acid protein with high similarity to known GTPase-activating proteins (GAPs).
- A recombinant fragment of p98 stimulated the GTPase activity of R-Ras, confirming its GAP function.
Conclusions:
- The purified protein, p98, is a novel GTPase-activating protein (GAP) for R-Ras.
- This novel R-Ras GAP plays a significant role in modulating R-Ras signaling pathways.
- The discovery provides new insights into the regulatory mechanisms of R-Ras in cellular functions.