Michaelis-Menten kinetics of RasGAP proteins by a rapid fluorescence-based assay.

ABSTRACT: Ras small GTPases are essential for a wide range of cellular processes. These proteins cycle between the GDP-loaded and GTP-loaded states, and the actions of GTPase activating proteins (GAPs) are necessary to stimulate Ras-mediated GTP hydrolysis. Here, we provide a protocol to achieve Michaelis-Menten kinetic profiling of GAP-mediated stimulation of a small GTPase by real-time monitoring of inorganic phosphate release in vitro. This is achieved using fluorescence of the Phosphate Sensor protein, an MDCC conjugate with periplasmic phosphate binding protein (PstS). We use H-Ras small GTPase pre-loaded with GTP and its stimulation by p120RasGAP (RasGAP, RASA1) as an example of this protocol. We discuss protocol design, assay development, data collection, processing, and analysis. Typical ass

SUBMITTER: Paul ME 

PROVIDER: S-EPMC12453608 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature