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Updated: Jun 4, 2025

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
Published on: March 9, 2012
Ionic control of small GTPase HRas using calmodulin.
Yassine Sabek1, Ziyun Zhang1, Nobuyuki Nishibe1
1Department of Biosciences, Graduate School of Science and Engineering, Soka University, 1-236 Tangi-cho, Hachioji, Tokyo 192-8577, Japan.
Engineered HRas fusion proteins, M13-HRas-M13, offer enhanced calcium-dependent control over GTPase activity and interactions with downstream signaling partners like Raf and GEF.
Area of Science:
- Molecular Biology
- Biochemistry
- Cell Signaling
Background:
- HRas is a small GTPase crucial for cell growth and proliferation, widely utilized in bionanomachines.
- Calmodulin (CaM) functions as a calcium-binding molecular switch, activating target enzymes.
- Previous work showed N-terminal M13-HRas fusion protein allows calcium-ion-dependent regulation of GTPase activity and Raf interaction.
Purpose of the Study:
- To engineer and analyze novel HRas fusion proteins (HRas-M13 and M13-HRas-M13) for calcium-dependent regulation.
- To investigate the impact of M13 peptide placement on HRas function.
- To assess the efficiency of calcium-ion-mediated control over HRas signaling.
Main Methods:
- Construction of two new HRas fusion proteins: HRas-M13 (C-terminal M13) and M13-HRas-M13 (N- and C-terminal M13).
- Analysis of calcium-dependent regulation of GTPase activity.
- Evaluation of calcium-ion-mediated interactions with downstream factors, including Raf and GEF.
Main Results:
- The M13-HRas-M13 fusion protein demonstrated enhanced calcium-dependent control over HRas GTPase activity.
- Calcium ions and CaM more effectively regulated the interaction between M13-HRas-M13 and its downstream targets, Raf and GEF.
- The placement of the M13 peptide significantly influenced the calcium-dependent modulation of HRas function.
Conclusions:
- HRas fusion proteins, particularly M13-HRas-M13, provide a robust platform for calcium-ion-switchable bionanomachines.
- Dual N- and C-terminal M13 peptide incorporation optimizes calcium-dependent regulation of HRas signaling pathways.
- This engineered system offers precise control over cellular processes regulated by HRas.
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