Nonradioactive Methods for Detecting Activation of Ras-Related Small G Proteins

  • Douglas A. Andres
Part of the Methods in Molecular Biology book series (MIMB, volume 284)


Ras-related small GTPases serve as critical regulators for a wide range of cellular signaling pathways and are activated by the conversion of the GDP-bound state to the GTP-bound conformation. Until recently, measurement of the GTP-bound active form of Ras-related G proteins involved immunoprecipitation of 32P-labeled protein followed by separation of the labeled GTP/GDP bound to GTPase. A new method based on the large affinity difference of the GTP- and GDP-bound form of Ras proteins for specific binding domains of effector proteins in vitro has been developed. By using glutathione S-transferase (GST) fusion proteins containing these binding domains, the GTP-bound form of the GTPase can be precipitated from cell lysates. In principle, this method can be used for all members of the Ras superfamily. Here we describe a general procedure to monitor the GTP-bound form of Ras-related GTPases.

Key Words

GTP-bound Ras GTPase activation probe 


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Copyright information

© Humana Press Inc., Totowa, NJ 2004

Authors and Affiliations

  • Douglas A. Andres
    • 1
  1. 1.Department of Molecular and Cellular BiochemistryUniversity of Kentucky College of MedicineLexington

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