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Updated: Aug 13, 2026

Characterization of G Protein-coupled Receptors by a Fluorescence-based Calcium Mobilization Assay
Published on: July 28, 2014
Assay for G protein-dependent activation of phospholipase C beta using purified protein components
1Department of Pharmacology and Physiology, University of Rochester School of Medicine, NY, USA.
Abstract:
The activity of mammalian phosphoinositide-specific phospholipase C beta (PLC beta) is regulated by the alpha q family of G protein alpha subunits and by beta gamma subunits thought to be released from Gi. Interactions between G protein subunits and PLC beta can be assayed by measuring the stimulation of PLC beta enzymatic activity on reconstituting the purified G protein subunits with purified PLC beta on artificial phospholipid vesicles containing the substrate, phosphatidylinositol-4,5-bisphosphate (PIP2). These vesicles are doped with [3H]-inositol PIP2 and the rate of hydrolysis is determined by quantitating the amount of [3H]-inositol triphosphate (IP3) released from the vesicle into the aqueous phase. This assay provides a relatively simple method for assessing the activity PLC activity and its ability to be regulated by beta gamma and alpha(q) subunits. It can also be used to assess the functionality of the components after modification by mutagenesis, chemical modification, or in the presence of competing molecules.
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