G protein betagamma complexes in circumvallate taste cells involved in bitter transduction

Chem Senses. 2000 Aug;25(4):413-21. doi: 10.1093/chemse/25.4.413.


G protein betagamma (Gbetagamma) complexes are considered to play an important role in second messenger signaling of phospholipase C (PLC). Monitoring the inositol 1,4,5-trisphosphate (IP(3)) response in circumvallate tissue homogenates upon stimulation with denatonium benzoate, it was demonstrated that a glutathione S-transferase-GRK3ct fusion protein-a Gbetagamma scavenger-attenuates the bitter tastant-induced second messenger reaction. Towards an identification of the Gbetagamma complex involved in rat bitter taste transduction, it was found that the G protein beta(3) subtype is specifically expressed in taste receptor cells of circumvallate papillae. Gbeta(3)-specific antibodies blocked the denatonium benzoate-induced IP(3) formation in a dose-dependent manner; the inhibitory effect was reversed by preincubation with the antigenic peptide. A less pronounced inhibition was observed using Gbeta(1)-specific antibodies. Analyzing individual taste cells by single cell reverse transcriptase-polymerase chain reaction approaches, overlapping expression patterns for PLCbeta(2), Galpha(gust), Gbeta(3) and Ggamma(3) could be demonstrated. Furthermore, the co-expression of all profiled signal transduction components in individual taste receptor cells could be detected. These data support the concept that the denatonium benzoate-induced IP(3) response is mediated by an activation of PLCbeta(2) via a Gbetagamma complex, possibly composed of Gbeta(3) as the predominant beta subunit and Ggamma(3), and imply that multiple second messenger pathways may exist in individual taste receptor cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • DNA Primers
  • GTP-Binding Proteins / metabolism
  • GTP-Binding Proteins / physiology*
  • Immunohistochemistry
  • Inositol 1,4,5-Trisphosphate / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / physiology*
  • Taste Buds / cytology
  • Taste Buds / metabolism
  • Taste Buds / physiology*


  • DNA Primers
  • Inositol 1,4,5-Trisphosphate
  • GTP-Binding Proteins