Related Experiment Video
Updated: Aug 19, 2026

Comparing the Affinity of GTPase-binding Proteins using Competition Assays
Published on: October 8, 2015
Cross GTPase-activating protein (CrossGAP)/Vilse links the Roundabout receptor to Rac to regulate midline repulsion
Hailan Hu1, Ming Li, Juan-Pablo Labrador
1Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
Abstract:
The regulators of the Rho-family GTPases, GTPase-activating proteins (GAPs) and guanine exchange factors (GEFs), play important roles in axon guidance. By means of a functional genomic study of the Rho-family GEFs and GAPs in Drosophila, we have identified a Rho-family GAP, CrossGAP (CrGAP), which is involved in Roundabout (Robo) receptor-mediated repulsive axon guidance. CrGAP physically associates with the Robo receptor. Too much or too little CrGAP activity leads to defects in Robo-mediated repulsion at the midline choice point. The CrGAP gain-of-function phenotype mimics the loss-of-function phenotypes of both Robo and Rac. Dosage-sensitive genetic interactions among CrGAP, Robo, and Rac support a model in which CrGAP transduces signals downstream of Robo receptor to regulate Rac-dependent cytoskeletal changes.
Related Concept Videos
Small GTPases - Ras and Rho
Three regulatory proteins control their activity:
Cell Polarization by Rho Proteins
Cytoskeletal Coordination in Cell Migration
Activation and Inactivation of G Proteins
Intracellular Signaling Affects Focal Adhesions
Some...
Mechanism of Lamellipodia Formation

