The neural G protein Gαo tagged with GFP at an internal loop is functional in C. elegans

Abstract

Go 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 Go remain to be fully elucidated. Genetic analysis in Caenorhabditis elegans has shown that Go 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 Go protein results in a tagged protein that is functional in vivo and that facilitates cell biological and biochemical studies of Go. Transgenic expression of Go-GFP rescues the defects caused by loss of endogenous Go in assays of egg laying and locomotion behaviors. Defects in body morphology caused by loss of Go are also rescued by Go-GFP. The Go-GFP protein is localized to the plasma membrane of neurons, mimicking localization of endogenous Go. Using GFP as an epitope tag, Go-GFP can be immunoprecipitated from C. elegans lysates to purify Go protein complexes. The Go-GFP transgene reported in this study enables studies involving in vivo localization and biochemical purification of Go to complement the already well-developed genetic analysis of Go signaling.