The neural G protein Gαotagged with GFP at an internal loop is functional inC. elegans

Gα o is the alpha subunit of the major heterotrimeric G protein in neurons and mediates signaling by every known neurotransmitter, yet the signaling mechanisms activated by Gα o remain to be fully elucidated. Genetic analysis in Caenorhabditis elegans has shown that Gα o signaling inhibits neuronal activity and neurotransmitter release, but studies of the molecular mechanisms underlying these effects have been limited by lack of tools to complement genetic studies with other experimental approaches. Here we demonstrate that inserting the green fluorescent protein (GFP) into an internal loop of the Gα o protein results in a tagged protein that is functional in vivo and that facilitates cell biological and biochemical studies of Gα o . Transgenic expression of Gα o -GFP rescues the defects caused by loss of endogenous Gα o in assays of egg laying and locomotion behaviors. Defects in body morphology caused by loss of Gα o are also rescued by Gα o -GFP. The Gα o -GFP protein is localized to the plasma membrane of neurons, mimicking localization of endogenous Gα o . Using GFP as an epitope tag, Gα o -GFP can be immunoprecipitated from C. elegans lysates to purify Gα o protein complexes. The Gα o -GFP transgene reported in this study enables studies involving in vivo localization and biochemical purification of Gα o to complement the already well-developed genetic analysis of Gα o signaling.