Channels as taste receptors in vertebrates.
Taste reception is fundamental for proper selection of food and beverages. Chemicals detected as taste stimuli by vertebrates include a large variety of substances, ranging from inorganic ions (e.g., Na(+), H(+)) to more complex molecules (e.g., sucrose, amino acids, alkaloids). Specialized epithelial cells, called taste receptor cells (TRCs), express specific membrane proteins that function as receptors for taste stimuli. Classical view of the early events in chemical detection was based on the assumption that taste substances bind to membrane receptors in TRCs without permeating the tissue. Although this model is still valid for some chemicals, such as sucrose, it does not hold for small ions, such as Na(+), that actually diffuse inside the taste tissue through ion channels. Electrophysiological, pharmacological, biochemical, and molecular biological studies have provided evidence that indeed TRCs use ion channels to reveal the presence of certain substances in foodstuff. In this review, we focus on the functional and molecular properties of ion channels that serve as receptors in taste transduction.
Bigiani
Albertino
A
Dipartimento di Scienze Biomediche, Sezione di Fisiologia, Università di Modena e Reggio Emilia, via Campi 287, 41100 Modena, Italy. bigiani@unimore.it
Ghiaroni
Valeria
V
Fieni
Francesca
F
D000818:Animals; D001001:Anura; D053503:Epithelial Sodium Channels; D006801:Humans; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D009337:Necturus; D024642:Potassium Channels, Voltage-Gated / Q000502:physiology; D011984:Sensory Receptor Cells / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D015222:Sodium Channels / Q000502:physiology; D013268:Stimulation, Chemical; D013650:Taste Buds / Q000502:physiology*
D053503:Epithelial Sodium Channels; D007473:Ion Channels; D024642:Potassium Channels, Voltage-Gated; D015222:Sodium Channels