Related Experiment Video
Updated: Jul 10, 2026
11:28
Affinity Precipitation of Active Rho-GEFs Using a GST-tagged Mutant Rho Protein (GST-RhoA(G17A)) from Epithelial Cell Lysates
Published on: March 31, 2012
Trio's Rho-specific GEF domain is the missing Galpha q effector in C. elegans
Stacey L Williams1, Susanne Lutz, Nicole K Charlie
1Program in Molecular, Cell, and Developmental Biology, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA.
Genes & Development
|October 19, 2007
Summary
The Galpha(q) pathway uses UNC-73 (Trio RhoGEF) and EGL-8 (PLCbeta) to control worm growth and movement. This study identifies Trio RhoGEF as a key effector in this essential signaling pathway.
Area of Science:
- Molecular Biology
- Cell Signaling
- Genetics
Background:
- The Galpha(q) pathway is vital for Caenorhabditis elegans development and behavior.
- This pathway regulates locomotion, egg laying, and growth.
- Its known effectors include EGL-8 (PLCbeta), but another effector was unidentified.
Purpose of the Study:
- To identify the missing effector of the Galpha(q) pathway.
- To elucidate the molecular mechanisms by which Galpha(q) signaling controls essential cellular functions.
Main Methods:
- Forward genetic screens were employed to identify suppressors of Galpha(q) pathway mutations.
- Mutational analysis of the identified suppressor gene, UNC-73 (Trio).
- Cell-based and biochemical assays, including co-immunoprecipitation, were used to validate interactions and functions.
Main Results:
- Four suppressor mutations identified disruptions in the UNC-73 (Trio RhoGEF) gene.
- UNC-73 RhoGEF acts with EGL-8 (PLCbeta) as a major Galpha(q) effector.
- Activated Galpha(q) and Trio RhoGEF synergize to activate RhoA and form a signaling complex.
- Double mutants (EGL-8 and UNC-73) phenocopied severe Galpha(q) loss-of-function phenotypes.
Conclusions:
- UNC-73 RhoGEF is a critical effector of the Galpha(q) pathway in C. elegans.
- The Galpha(q)-Trio-RhoA signaling axis is essential for locomotion, egg laying, and growth.
- This pathway highlights a conserved mechanism for regulating cellular processes through G protein signaling.
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:
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...
01:14Rab Proteins
Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
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,...
02:38The Ras Gene
The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...
Ras is a superfamily...
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.