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CAPRI regulates Ca(2+)-dependent inactivation of the Ras-MAPK pathway
P J Lockyer1, S Kupzig, P J Cullen
1Department of Biochemistry, School of Medical Sciences, University of Bristol, BS8 1TD, Bristol, United Kingdom. P.J.Lockyer@bristol.ac.uk
Current Biology : CB
|July 13, 2001
Summary
Calcium (Ca2+) activates Ras signaling, but a direct inactivation mechanism was unknown. Researchers discovered CAPRI, a Ca2+-dependent Ras GTPase-activating protein (GAP) that inactivates the Ras-MAPK pathway via Ca2+-mediated translocation.
Area of Science:
- Cellular signaling
- Molecular biology
- Biochemistry
Background:
- Calcium (Ca2+) acts as a universal second messenger regulating cell growth, proliferation, and differentiation.
- Ras proteins are key molecular switches controlling gene expression and cell growth pathways.
- While Ca2+ can activate Ras, a direct Ca2+-dependent inactivation mechanism was previously unidentified.
Purpose of the Study:
- To identify and characterize novel Ca2+-dependent regulators of Ras signaling.
- To elucidate the mechanism by which Ca2+ influences the Ras-MAPK pathway.
- To understand the spatio-temporal dynamics of Ras signaling regulation.
Main Methods:
- Identification of Ca(2+)-promoted Ras inactivator (CAPRI).
- Biochemical assays to determine CAPRI's GTPase-activating protein (GAP) activity.
- Spatio-temporal analysis of CAPRI dynamics in vivo.
- Investigation of Ca2+ regulation via C2 domain-dependent translocation.
Main Results:
- Discovery of CAPRI, a novel Ca2+-dependent Ras GTPase-activating protein (GAP).
- CAPRI directly inactivates the Ras-MAPK pathway in response to elevated intracellular Ca2+.
- Ca2+ regulates CAPRI activity through a rapid C2 domain-dependent translocation mechanism.
Conclusions:
- CAPRI represents the first identified Ca2+-dependent mechanism for direct Ras inactivation.
- This finding provides new insights into the complex coordination of the Ras-signaling network.
- The Ca2+-dependent translocation of CAPRI offers a novel regulatory mechanism for controlling cell growth and differentiation pathways.