Coupling of bitter receptor to phosphodiesterase through transducin in taste receptor cells

Nature. 1995 Jul 6;376(6535):80-5. doi: 10.1038/376080a0.


The rod and cone transducins are specific G proteins originally thought to be present only in photoreceptor cells of the vertebrate retina. Transducins convert light stimulation of photoreceptor opsins into activation of cyclic GMP phosphodiesterase (reviewed in refs. 5-7). A transducin-like G protein, gustducin, has been identified and cloned from rat taste cells. We report here that rod transducin is also present in vertebrate taste cells, where it specifically activates a phosphodiesterase isolated from taste tissue. Furthermore, the bitter compound denatonium in the presence of taste-cell membranes activates transducin but not Gi. A peptide that competitively inhibits rhodopsin activation of transducin also blocks taste-cell membrane activation of transducin, arguing for the involvement of a seven-transmembrane-helix G-protein-coupled receptor. These results suggest that rod transducin transduces bitter taste by coupling taste receptor(s) to taste-cell phosphodiesterase. Phosphodieterase-mediated degradation of cyclic nucleotides may lead to taste-cell depolarization through the recently identified cyclic-nucleotide-suppressible conductance.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cattle
  • Enzyme Activation
  • GTP-Binding Proteins / metabolism
  • Phosphoric Diester Hydrolases / metabolism*
  • Photoreceptor Cells / metabolism
  • Polymerase Chain Reaction
  • Precipitin Tests
  • Quaternary Ammonium Compounds / pharmacology
  • RNA, Messenger / metabolism
  • Rats
  • Rhodopsin / metabolism
  • Taste Buds / drug effects
  • Taste Buds / enzymology
  • Taste Buds / metabolism*
  • Transducin / metabolism*


  • Quaternary Ammonium Compounds
  • RNA, Messenger
  • denatonium benzoate
  • Rhodopsin
  • Phosphoric Diester Hydrolases
  • GTP-Binding Proteins
  • Transducin