The structure of Ras protein: a model for a universal molecular switch
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1Abteilung Biophysik, Max-Planck-Institut für Medizinische Forschung, Heidelberg, FRG.
Abstract:
X-ray crystallography has revealed the molecular architecture of the cellular and oncogenic forms of p21Ha-ras, the protein encoded by the human Ha-ras gene, in both its active (GTP-bound) and in its inactive (GDP-bound) forms. From comparison of these two structures, a mechanism is suggested for the GTPase hydrolysis reaction that triggers the conformational change necessary for signal transduction. The structures have also allowed identification of the structural consequences of point mutations and the way in which they interfere with the intrinsic GTPase activity of p21ras. The p21ras structure is similar to that of the G-domain of elongation factor Tu (EF-Tu) from Escherichia coli, suggesting that p21ras can serve as a good model for other guanine nucleotide binding proteins.
Insights
X-ray crystallography reveals the molecular structures of the p21Ha-ras protein in active and inactive states. This provides insights into GTPase mechanisms, signal transduction, and how mutations affect p21ras function.
Area of Science:
- Molecular biology
- Structural biology
- Biochemistry
Background:
- The human Ha-ras gene encodes the p21Ha-ras protein, a key regulator in cellular signaling.
- Understanding the structural basis of p21Ha-ras function is crucial for deciphering signal transduction pathways and oncogenesis.
Purpose of the Study:
- To elucidate the molecular architecture of both cellular and oncogenic forms of p21Ha-ras.
- To determine the structural differences between the active (GTP-bound) and inactive (GDP-bound) states of p21Ha-ras.
- To investigate the structural impact of point mutations on p21ras GTPase activity and function.
Main Methods:
- X-ray crystallography was employed to determine the high-resolution structures of p21Ha-ras.
- Comparative analysis of the GTP-bound and GDP-bound p21Ha-ras structures.
Main Results:
- Detailed molecular architecture of p21Ha-ras in its active and inactive forms was revealed.
- A mechanism for the GTPase hydrolysis reaction, linked to signal transduction, was proposed based on structural comparisons.
- Structural consequences of point mutations interfering with p21ras intrinsic GTPase activity were identified.
Conclusions:
- The structural data provides a mechanistic understanding of p21ras GTPase activity and its role in signal transduction.
- p21Ha-ras serves as a valuable model for other guanine nucleotide-binding proteins, evidenced by structural similarities to E. coli EF-Tu.
- Understanding p21ras structure-function relationships is critical for comprehending oncogenic mutations and developing targeted therapies.