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Updated: Aug 12, 2026

Quantifying Agonist Activity at G Protein-coupled Receptors
Published on: December 26, 2011
Expression levels of RGS7 and RGS4 proteins determine the mode of regulation of the G protein-activated K(+) channel
T Keren-Raifman1, A K Bera, D Zveig
1Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel. raifmant@yahoo.com
Abstract:
Regulators of G protein signaling RGS4 and RGS7 accelerate the kinetics of K(+) channels (GIRKs) in the Xenopus oocyte system. Here, via quantitative analysis of RGS expression, we reveal biphasic effects of RGSs on GIRK regulation. At low concentrations, RGS4 inhibited basal GIRK activity, but stimulated it at high concentrations. RGS7, which is associated with the G protein subunit G beta 5, is regulated by G beta 5 by two distinct mechanisms. First, G beta 5 augments RGS7 activity, and second, it increases its expression. These dual effects resolve previous controversies regarding RGS4 and RGS7 function and indicate that they modulate signaling by mechanisms supplementary to their GTPase-activating protein activity.
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