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Updated: May 30, 2026

Analyzing the Function of Small GTPases by Microinjection of Plasmids into Polarized Epithelial Cells
Published on: May 31, 2011
Regulation of small GTPases at epithelial cell-cell junctions
Sandra Citi1, Domenica Spadaro, Yann Schneider
1Department of Molecular Biology, University of Geneva, Geneva, Switzerland. sandra.citi@unige.ch
Abstract:
Small GTPases of the Rho family (RhoA, Rac1, and Cdc42) and the Ras family GTPase Rap1 are essential for the assembly and function of epithelial cell-cell junctions. Through their downstream effectors, small GTPases modulate junction formation and stability, primarily by orchestrating the polymerization and contractility of the actomyosin cytoskeleton. The major upstream regulators of small GTPases are guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). Several GEFs and a few GAPs have been localized at epithelial junctions, and bind to specific junctional proteins. Thus, junctional proteins can regulate small GTPases at junctions, through their interactions with GEFs and GAPs. Here we review the current knowledge about the mechanisms of regulation of small GTPases by junctional proteins. Understanding these mechanisms will help to clarify at the molecular level how small GTPases control the morphogenesis and physiology of epithelial tissues, and how they are disregulated in disease.
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