Related Experiment Video
Updated: May 15, 2026
09:58
RhoC GTPase Activation Assay
Published on: August 22, 2010
Computational analysis of Rho GTPase cycling
Cibele Vieira Falkenberg1, Leslie M Loew
1Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, Connecticut, United States of America.
Plos Computational Biology
|January 18, 2013
Summary
Rho GTPases regulate cell functions by cycling between the cell membrane and cytosol. This study models GTPase cycling to reveal how Guanine nucleotide Dissociation Inhibitors (GDIs) control these processes, aiding in understanding diseases.
Area of Science:
- Cell Biology
- Biochemistry
- Systems Biology
Background:
- Rho family GTPases (RhoA, Rac, Cdc42) are critical regulators of actin organization in cellular processes like migration and endocytosis.
- GTPase activation involves membrane targeting and GTP binding, but upstream regulation details remain unclear.
- Guanine nucleotide Dissociation Inhibitors (GDIs) play a role in GTPase cycling between the membrane and cytosol.
Purpose of the Study:
- To develop a modeling framework to analyze GTPase cycling dynamics between the membrane and cytosol.
- To investigate the role of GDI-mediated cycling in the differential regulation of Rho GTPases.
- To distinguish between GDI-dependent and -independent mechanisms of GTPase membrane association.
Main Methods:
- Development of a computational modeling framework to analyze experimental data on GTPase cycling.
- Analysis of Rac GTPase membrane cycling kinetics, focusing on GDI interactions with GDP- and GTP-bound states.
- Generation of non-dimensional steady-state charts to visualize GTPase membrane fractions under various conditions.
Main Results:
- The lower apparent affinity of GDI for RacGTP versus RacGDP is explained by faster dissociation of RacGDP from the membrane.
- Modeling charts effectively illustrate the impact of Guanine nucleotide Exchange Factors (GEFs), GTPase Activating Proteins (GAPs), and varying affinities on membrane-bound GTPase levels.
- The framework successfully analyzes glucose-stimulated Rac cycling in pancreatic beta-cells.
Conclusions:
- GTPase cycling dynamics, particularly GDI-mediated mechanisms, are crucial for differential upstream regulation of Rho GTPases.
- The developed modeling framework and visualization charts provide a valuable tool for analyzing GTPase regulation.
- This approach can guide strategies for compensating altered GTPase-GDI balance in disease contexts.
Related Concept Videos
01:24Small GTPases - Ras and Rho
Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
Three regulatory proteins control their activity:
02:14GTPases and their Regulation
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Large G-proteins, also known...
02:14GTPases and their Regulation
Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒ small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Large G-proteins, also known...
01:25Rab Cascades
Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.
01:21Cell Polarization by Rho Proteins
Cell polarity is the asymmetric distribution of cellular and membrane components, making one side of the cell different from the other. This polarity is essential to many processes such as embryogenesis, axon migration, glucose transport across epithelial cells, and directional cell migration. A migrating cell responds to intracellular or extracellular signals via molecular cascades that reorganize the actin cytoskeleton to establish this polarity. In these cells, the Rho family proteins Cdc42,...
01:22Activation and Inactivation of G Proteins
Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...