Gustducin and Transducin: A Tale of two G Proteins

  1. Derek Chadwick Organizer,
  2. Joan Marsh Organizer and
  3. Jamie Goode
  1. Susan K. McLaughlin,
  2. Peter J. McKinnon,
  3. Alain Robichon,
  4. Nancy Spickofsky and
  5. Robert F. Margolskee

Published Online: 28 SEP 2007

DOI: 10.1002/9780470514511.ch12

Ciba Foundation Symposium 179 - The Molecular Basis of Smell and Taste Transduction

Ciba Foundation Symposium 179 - The Molecular Basis of Smell and Taste Transduction

How to Cite

McLaughlin, S. K., McKinnon, P. J., Robichon, A., Spickofsky, N. and Margolskee, R. F. (2007) Gustducin and Transducin: A Tale of two G Proteins, in Ciba Foundation Symposium 179 - The Molecular Basis of Smell and Taste Transduction (eds D. Chadwick, J. Marsh and J. Goode), John Wiley & Sons, Ltd., Chichester, UK. doi: 10.1002/9780470514511.ch12

Author Information

  1. Roche Research Center, Roche Institute of Molecular Biology, Roche Research Center, 340 Kingsland Street, Nutley, NJ 07110-1199, USA

Publication History

  1. Published Online: 28 SEP 2007

ISBN Information

Print ISBN: 9780471939467

Online ISBN: 9780470514511

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Keywords:

  • gustducin;
  • transducin;
  • G proteins;
  • polymerase chain reaction;
  • inositol trisphosphate

Summary

In the vertebrate taste cell, heterotrimeric guanine nucleotide-binding proteins (G proteins) are involved in the transduction of both bitter and sweet taste stimulants. The bitter compound denatonium raises the intracellular Ca2+ concentration in rat taste cells, apparently via G protein-mediated increases in inositol trisphosphate. Sucrose causes a G protein-dependent generation of cAMP in rat taste bud membranes; elevation of cAMP levels leads to taste cell depolarization. To identify and characterize those proteins involved in the taste transduction process, we have cloned G protein α subunit (Gα) cDNAs from rat taste cells. Using degenerate primers corresponding to conserved regions of G proteins, we used the polymerase chain reaction to amplify and clone taste cell Gα cDNAs. Eight distinct Gα cDNAs were isolated, cloned and sequenced from a taste cell library. Among these clones was α gustducin, a novel taste Gα closely related to the transducins. In addition to α gustducin, we cloned rod and cone transducins from taste cells. This is the first identification of transducin expression outside photoreceptor cells. The primary sequence of α gustducin shows similarities to the transducins in the receptor interaction domain and the phosphodiesterase activation site. These sequence similarities suggest that gustducin and transducin regulate taste cell phosphodiesterase, probably in bitter taste transduction.