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Nat Chem Biol. 2016 Oct;12(10):802-809. doi: 10.1038/nchembio.2145. Epub 2016 Aug 8.

FRET binding antenna reports spatiotemporal dynamics of GDI-Cdc42 GTPase interactions.

Author information

Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine.
Department of Pharmacology and Lineberger Cancer Center, University of North Carolina at Chapel Hill.
Department of Cell Biology, The Scripps Research Institute.
Department of Immunology and Microbial Science, The Scripps Research Institute.
Department of Cell Biology, Harvard Medical School.
Contributed equally


Guanine-nucleotide dissociation inhibitors (GDIs) are negative regulators of Rho family GTPases that sequester the GTPases away from the membrane. Here we ask how GDI-Cdc42 interaction regulates localized Cdc42 activation for cell motility. The sensitivity of cells to overexpression of Rho family pathway components led us to a new biosensor, GDI.Cdc42 FLARE, in which Cdc42 is modified with a fluorescence resonance energy transfer (FRET) 'binding antenna' that selectively reports Cdc42 binding to endogenous GDIs. Similar antennae could also report GDI-Rac1 and GDI-RhoA interaction. Through computational multiplexing and simultaneous imaging, we determined the spatiotemporal dynamics of GDI-Cdc42 interaction and Cdc42 activation during cell protrusion and retraction. This revealed remarkably tight coordination of GTPase release and activation on a time scale of 10 s, suggesting that GDI-Cdc42 interactions are a critical component of the spatiotemporal regulation of Cdc42 activity, and not merely a mechanism for global sequestration of an inactivated pool of signaling molecules.

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