A Global Map of G Protein Signaling Regulation by RGS Proteins

The control over the extent and timing of G protein signaling is provided by the regulator of G protein signaling (RGS) proteins that deactivate G protein a subunits (G alpha). Mammalian genomes encode 20 canonical RGS and 16 G alpha genes with key roles in physiology and disease. To understand the principles governing the selectivity of G alpha regulation by RGS, we examine the catalytic activity of all canonical human RGS proteins and their selectivity for a complete set of G alpha substrates using real-time kinetic measurements in living cells. The data reveal rules governing RGS-G alpha recognition, the structural basis of its selectivity, and provide principles for engineering RGS proteins with defined selectivity. The study also explores the evolution of RGS-G alpha selectivity through ancestral reconstruction and demonstrates how naturally occurring non-synonymous variants in RGS alter signaling. These results provide a blueprint for decoding signaling selectivity and advance our understanding of molecular recognition principles.