A G Protein γ Subunit-Like Domain Shared between RGS11 and Other RGS Proteins Specifies Binding to Gβ 5 Subunits

Regulators of G protein signaling (RGS) proteins act as GTPase-activating proteins (GAPs) toward the α subunits of heterotrimeric, signal-transducing G proteins. RGS11 contains a G protein γ subunit-like (GGL) domain between its Dishevelled/Egl-10/Pleckstrin and RGS domains. GGL domains are also found in RGS6, RGS7, RGS9, and the Caenorhabditis elegans protein EGL-10. Coexpression of RGS11 with different G_β subunits reveals specific interaction between RGS11 and G_β5. The expression of mRNA for RGS11 and G_β5 in human tissues overlaps. The G_β5/RGS11 heterodimer acts as a GAP on G_αo, apparently selectively. RGS proteins that contain GGL domains appear to act as GAPs for G_α proteins and form complexes with specific G_β subunits, adding to the combinatorial complexity of G protein-mediated signaling pathways.