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Updated: Jun 21, 2026
07:51
Pull-down of Calmodulin-binding Proteins
Published on: January 23, 2012
The hypervariable region of K-Ras4B is responsible for its specific interactions with calmodulin
Sherwin J Abraham1, Ryan P Nolet, Richard J Calvert
1Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607, USA.
Biochemistry
|July 9, 2009
Summary
K-Ras4B
Area of Science:
- Molecular Biology
- Cell Signaling
- Biochemistry
Background:
- K-Ras4B is a p21 Ras GTPase crucial for cell functions.
- Ras isoforms share high homology but have unique roles.
- Understanding Ras isoform specificity is key to signaling pathway regulation.
Purpose of the Study:
- To investigate the specific binding interaction between K-Ras4B and calmodulin.
- To elucidate the roles of K-Ras4B's hypervariable region and catalytic domain in this interaction.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy.
- Isothermal Titration Calorimetry (ITC).
Main Results:
- The hypervariable region of K-Ras4B significantly mediates calmodulin binding.
- K-Ras4B's catalytic domain, via nucleotide binding, regulates this interaction.
- Specific binding occurs between K-Ras4B's hypervariable region and Ca(2+)-loaded calmodulin's C-terminal domain (micromolar affinity).
- The GTP-gamma-S-loaded catalytic domain of K-Ras4B may interact with calmodulin's N-terminal domain.
Conclusions:
- K-Ras4B's unique C-terminal hypervariable region is critical for specific calmodulin interaction.
- Nucleotide binding to K-Ras4B's catalytic domain modulates calmodulin binding, suggesting a regulatory mechanism.
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