Related Experiment Video
Updated: Sep 21, 2026

A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators
Published on: February 20, 2018
Modulation of 5-HT(1A) receptor-mediated Ca(2+) responses by co-expression with various recombinant G(alpha) proteins
Thierry Wurch1, Petrus J Pauwels
1Department of Cellular and Molecular Biology, Centre de Recherche Pierre Fabre, 17, avenue Jean Moulin, 81106, Castres Cédex, France.
Abstract:
The ability of the human 5-HT(1A) receptor to activate different recombinant G(alpha) proteins was investigated in CHO-K1 cells by monitoring 5-HT ligand-mediated Ca(2+) responses upon co-expression with either G(alphaq), G(alpha15) or chimeric G(alphaq/i3) proteins. Each G(alpha) protein yielded a typical 5-HT-dependent Ca(2+) response with different kinetic parameters both for the onset-time of maximal Ca(2+) response (21 to 30 s) and time-dependent attenuation (43 to 73% of residual activity at 1 min upon peak Ca(2+) response). Pertussis toxin-treatment fully abolished the Ca(2+) responses mediated by both the endogenous G(i/o) and the chimeric-PTX-sensitive G(alphaq/i3) proteins. In contrast, Ca(2+) responses driven by recombinant G(alphaq) and G(alpha15) proteins were decreased by PTX, respectively by 52% and 35%, corresponding to the level of endogenous G protein activation. The pharmacology of the 5-HT ligand-mediated Ca(2+) responses was highly affected by both the presence and nature of the co-expressed G(alpha) protein. This influence was more pronounced for the partial agonists L 694247, 8-OH-DPAT, flesinoxan and buspirone in contrast to ipsapirone. The G(alpha) protein rank order for apparent increase of ligands' intrinsic activity was: G(alphaq)
More Related Videos
Related Concept Videos
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
G-Protein Gated Ion Channels
Sensory organs,...
Cholinergic Receptors: Muscarinic
The subtypes M1, M3, and M5 couple with the Gq subunit and activate the phospholipase C (PLC) activity, mobilizing intracellular Ca2+. Activation...
GPCRs Regulate Adenylyl Cylase Activity
Two...
Activation and Inactivation of G Proteins
G Protein-coupled Receptors

