Regulators of G protein signaling (RGS) are GTPase-accelerating proteins (GAPs), which
can inhibit heterotrimeric G protein pathways. In this study, we provide experimental and
theoretical evidence that high concentrations of receptors (as at a synapse) can lead to
saturation of GDP-GTP exchange making GTP hydrolysis rate-limiting. This results in local
depletion of inactive heterotrimeric G-GDP, which is reversed by RGS GAP activity. Thus,
RGS enhances receptor-mediated G protein activation even as it deactivates the G protein …