PSY 3126 Lecture Notes - Lecture 3: Tas1R1, Inositol Trisphosphate, Tas1R2
24 Jan 2013
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The process by which an environmental stimulus causes an electrical response in a sensory receptor cell is called transduction. Taste transduction involves several different processes and each basic taste uses one or more of these mechanisms: Directly pass through ion channels (salt and sour) Bind to g-protein-coupled receptors in the membrane that activate second messenger systems. The taste of salt is mostly the taste of the cation na+ and its concentration must be quite high in order to taste it (at least 10 nm). Salt-sensitive taste cells have a special na+-selective channel that is blocked by the drug amiloride (see fig. This channel is insensitive to voltage and is always open. When you sip chick soup, for example, the na+ concentration rises outside the receptor cell. Na+ then diffuses down its concentration gradient which results in an inward current and depolarization (receptor potential) of the membrane.
