“…Although the research work with a use of this technique has provided us with invaluable results regarding physiological, pharmacological, and pathological functionality of G protein-mediated signal transduction stimulated by many metabotropic receptors, it is usually applicable preferentially to G i/o proteins, through which the inhibitory receptors are negatively coupled with adenylyl cyclase, especially in native brain membranes. More recently, the antibody-capture [ 35 S]GTPcS scintillation proximity assay (SPA), in which immuno-capture of Ga subunits following [ 35 S]GTPcS binding is combined with the SPA technology (Kahl and Felder 2005), has been newly developed to investigate the specific interactions between several G protein-coupled receptors (GPCRs) and Ga subunits, even in native brain membranes (DeLapp 2004). Using the membranes prepared from rodent brain regions, functional activation of Ga subunits have been reported for Ga q/11 , Ga i(1-3) , and Ga o coupled with muscarinic acetylcholine receptors (mAChRs) in rat striatum (DeLapp et al 1999), Ga q/11 coupled with M 1 mAChR in mouse hippocampus and cortex (Porter et al 2002), Ga o and Ga i3 in rat hippocampus and Ga i3 in rat anterior raphe coupled with 5-HT 1A receptors (Mannoury la Cour et al 2006), Ga s/olf and Ga q coupled with dopamine D 1 receptors in rat striatum and cortex (Mannoury la Cour et al 2007), Ga o coupled with 5-HT 1A receptors in rat hippocampus (Martel et al 2007), and Ga o and Ga i1/3 coupled with GABA B receptors in rat cortex, hippocampus, and cerebellum (Mannoury la Cour et al 2008).…”