Related Experiment Video
Updated: Jul 26, 2026

Pull-down of Calmodulin-binding Proteins
Published on: January 23, 2012
Calcium and calmodulin are essential for Ras-GRF1-mediated activation of the Ras pathway by lysophosphatidic acid
R Zippel1, M Balestrini, M Lomazzi
1Department of General Physiology and Biochemistry, University of Milan, Via Celoria, 26, Milan, 20133, Italy.
Abstract:
The exchange factor Ras-GRF1, also called CDC25Mm, couples calcium signaling and G-protein-coupled receptors to Ras and downstream effectors. Here we show that when expressed in different cell lines Ras-GRF1 strongly enhances the level of active Ras (Ras-GTP) and the activity of mitogen-activated protein kinases (MAPK). Moreover, in NIH 3T3 fibroblasts it potentiates the effect of lysophosphatidic acid (LPA) on Ras protein and MAPK activity. Calmodulin and cytosolic free calcium are essential for Ras and MAPK activation induced by LPA and mediated by Ras-GRF1, as shown by the finding that BAPTA-AM, an intracellular calcium chelator, and calmodulin inhibitors completely abolished this effect. This report demonstrates the relevance of calmodulin in addition to calcium for the response of Ras-GRF1 to LPA.
Related Concept Videos
The Ras Gene
Ras is a superfamily...
Non-Canonical Wnt Signaling Pathways
Small GTPases - Ras and Rho
Three regulatory proteins control their activity:
MAPK Signaling Cascades
IP3/DAG Signaling Pathway
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...

