Related Experiment Video
Updated: May 23, 2026

RhoC GTPase Activation Assay
Published on: August 22, 2010
The TOR complex 1 is a direct target of Rho1 GTPase
Gonghong Yan1, Yumei Lai, Yu Jiang
1Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
Abstract:
The TOR complex 1 (TORC1) in yeast is regulated by various stress conditions. However, the underlying mechanism is poorly understood. In this study, we show that stresses affect TORC1 function through Rho1, a member of Rho family GTPases. Upon activation by stresses, Rho1 binds directly to Kog1, a unique component of TORC1, resulting in downregulation of TORC1 activity and disruption of its membrane association. The binding also triggers the release and activation of the Tap42-2A phosphatase, a major effector of TORC1 that resides on the complex. Rapamycin and caffeine also induce Rho1 activation. While the two agents inhibit TOR directly, their effects on TORC1 signaling are largely dependent on Rho1 activation. Our findings demonstrate that TORC1 acts both upstream and downstream of Rho1 GTPase, unveiling a mechanism that integrates stress and nutrient signals to coordinate Rho1-mediated spatial expansion and TORC1-dependent mass increase.
Related Concept Videos
Small GTPases - Ras and Rho
Three regulatory proteins control their activity:
Rab Proteins
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...
Activation and Inactivation of G Proteins
PI3K/mTOR/AKT Signaling Pathway
Receptor Tyrosine Kinases
The Ras Gene
Ras is a superfamily...

