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Characterization of the structural difference between active and inactive forms of the Ras protein by chemical
S Akashi1, M Shirouzu, T Terada
1Division of Biomolecular Characterization, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
Abstract:
Ras is one of the guanosine triphosphate (GTP) binding proteins that plays a significant role in signaling events of cell growth and differentiation. It can exist in two states: guanosine diphosphate (GDP)-bound from (Ras.GDP; inactive) and GTP-bound form (Ras.GTP; active). This paper discusses the difference in tertiary structure between the active and inactive forms using the combination of chemical modification and mass spectrometry. This difference can be clearly recognized in the presence of a target protein. Raf-1 RBD (Raf-1 Ras-binding domain), as differing glycinamidation of carboxyl groups. It was possible to observe the difference between these two states using several hundred picomoles of sample. While it is true that it is difficult to obtain the whole picture of a protein by the combination of chemical modification and mass spectrometry, it is a promising approach for the characterization of surface structure using very small amounts of sample.
Insights
This study reveals structural differences between active and inactive Ras proteins using chemical modification and mass spectrometry. This method allows for the characterization of protein surface structures with minimal sample. Keywords: Ras proteins, structural differences, mass spectrometry.
Area of Science:
- Molecular Biology
- Biochemistry
- Proteomics
Background:
- Ras proteins are key regulators of cell growth and differentiation, cycling between inactive GDP-bound and active GTP-bound states.
- Understanding the structural differences between these states is crucial for deciphering Ras signaling pathways.
Purpose of the Study:
- To investigate the tertiary structural differences between active (Ras.GTP) and inactive (Ras.GDP) forms of Ras proteins.
- To evaluate the utility of chemical modification coupled with mass spectrometry for characterizing these structural variations.
Main Methods:
- Utilized chemical modification, specifically glycinamidation of carboxyl groups, to probe protein structure.
- Employed mass spectrometry to detect and analyze structural differences induced by chemical modification.
- Investigated structural changes in the presence of a target protein, Raf-1 Ras-binding domain (RBD).
Main Results:
- Distinct differences in tertiary structure between active and inactive Ras proteins were identified.
- These structural variations were clearly discernible in the presence of Raf-1 RBD.
- The method successfully detected these differences using only several hundred picomoles of sample.
Conclusions:
- Chemical modification combined with mass spectrometry is a powerful approach for characterizing Ras protein structural states.
- This technique enables the analysis of protein surface structures using very small sample quantities.
- The findings provide insights into Ras protein conformational changes during signaling.