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Updated: Aug 6, 2026

Characterization of G Protein-coupled Receptors by a Fluorescence-based Calcium Mobilization Assay
Published on: July 28, 2014
Effect of Li+ upon the Mg2+-dependent activation of recombinant Gialpha1
N Minadeo1, B Layden, L V Amari
1Department of Chemistry, Loyola University at Chicago, Illinois 60626, USA.
Abstract:
Although lithium salts have been used in the treatment and prophylaxis of manic-depressive or bipolar patients for 50 years, the mechanism of the pharmacologic action of Li+ is unknown. Based on activity studies of inhibitory and stimulatory guanine-binding (G) proteins in rat cortical membranes, it was proposed that Li+ inhibition of G-proteins may account for its pharmacologic action. We used the purified alpha subunit of the recombinant inhibitory G-protein, rGialpha1, and found that Li+ at therapeutic levels significantly inhibited the formation of the GDP.AlF4-.rGialpha1 complex. Because our studies were conducted with a purified, metal-reconstituted G-protein rather than with cell membrane suspensions, our Li+ inhibition results lend additional support to the G-protein hypothesis for Li+ action.
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