A metabotropic glutamate receptor variant functions as a taste receptor

Sensory transduction for many taste stimuli such as sugars, some bitter com pounds and amino acids is thought to be mediated via G protein-coupled rece ptors (GPCRs), although no such receptors that respond to taste stimuli are yet identified. Monosodium L-glutamate (L-MSG), a natural component of man y foods, is an important gustatory stimulus believed to signal dietary prot ein. We describe a GPCR cloned from rat taste buds and functionally express ed in CHO cells. The receptor couples negatively to a cAMP cascade and show s an unusual concentration-response relationship. The similarity of its pro perties to MSG taste suggests that this receptor is a taste receptor for gl utamate.