The G-Protein β-Subunit GPB-2 in Caenorhabditis elegans Regulates the Goα-Gqα Signaling Network Through Interactions With the Regulator of G-Protein Signaling Proteins EGL-10 and EAT-16

The genome of Caenorhabditis elegans harbors two genes for G-protein β-subunits. Here, we describe the characterization of the second G-protein β-subunit gene gpb-2. In contrast to gpb-1, gpb-2 is not an essential gene even though, like gpb-1, gpb-2 is expressed during development, in the nervous system, and in muscle cells. A loss-of-function mutation in gpb-2 produces a variety of behavioral defects, including delayed egg laying and reduced pharyngeal pumping. Genetic analysis shows that GPB-2 interacts with the GOA-1 (homologue of mammalian Goα) and EGL-30 (homologue of mammalian Gqα) signaling pathways. GPB-2 is most similar to the divergent mammalian Gβ5 subunit, which has been shown to mediate a specific interaction with a Gγ-subunit-like (GGL) domain of RGS proteins. We show here that GPB-2 physically and genetically interacts with the GGL-containing RGS proteins EGL-10 and EAT-16. Taken together, our results suggest that GPB-2 works in concert with the RGS proteins EGL-10 and EAT-16 to regulate GOA-1 (Goα) and EGL-30 (Gqα) signaling.