Tonic activity of Gα‐gustducin regulates taste cell responsivity

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Abstract
The taste‐selective G protein, α‐gustducin (α‐gus) is homologous to α‐transducin and activates phosphodiesterase (PDE) in vitro. α‐Gus‐knockout mice are compromized to bitter, sweet and umami taste stimuli, suggesting a central role in taste transduction. Here, we suggest a different role for Gα‐gus. In taste buds of α‐gus‐knockout mice, basal (unstimulated) cAMP levels are high compared to those of wild‐type mice. Further, H‐89, a cAMP‐dependent protein kinase inhibitor, dramatically unmasks responses to the bitter tastant denatonium in gus‐lineage cells of knockout mice. We propose that an important role of α‐gus is to maintain cAMP levels tonically low to ensure adequate Ca2+ signaling.