The present invention features G-protein fusion receptors and chimeric GABA.sub.B receptors (GABA.sub.BRs), nucleic acid encoding such receptors, and the use of such receptors and nucleic acid. G-protein fusion receptors comprise at least one domain from a CaR, an mGluR, and/or a GABA.sub.B receptor fused directly or through a linker to a guanine nucleotide-binding protein (G-protein). Chimeric GABA.sub.BRs comprise at least one of a GABA.sub.BR extracellular domain, a GABA.sub.BR transmembrane domain, or a GABA.sub.BR intracellular domain and one or more domains from a mGluR subtype 8 (mGluR8) and/or a CaR.