Coding of Sweet, Bitter, and Umami Tastes: Different Receptor Cells Sharing Similar Signaling Pathways

• Published in: Cell Vol. 112; no. 3; pp. 293 - 301
• Main Authors: Zhang, Yifeng, Hoon, Mark A., Chandrashekar, Jayaram, Mueller, Ken L., Cook, Boaz, Wu, Dianqing, Zuker, Charles S., Ryba, Nicholas J.P.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07-02-2003
• Subjects: Action Potentials - drug effects; Action Potentials - physiology; Animals; Cell Membrane - drug effects; Cell Membrane - metabolism; Cells, Cultured; Citric Acid - pharmacology; Female; Glutamic Acid - pharmacology; GTP-Binding Proteins - drug effects; GTP-Binding Proteins - metabolism; Isoenzymes - deficiency; Isoenzymes - genetics; Male; Membrane Proteins - deficiency; Membrane Proteins - genetics; Mice; Mice, Knockout; Neurons, Afferent - drug effects; Neurons, Afferent - physiology; Phospholipase C beta; Quinine - pharmacology; Receptors, Cell Surface - drug effects; Receptors, Cell Surface - metabolism; Sensory Receptor Cells - drug effects; Sensory Receptor Cells - physiology; Signal Transduction - drug effects; Signal Transduction - physiology; Sucrose - pharmacology; Taste - drug effects; Taste - genetics; Taste Buds - cytology; Taste Buds - drug effects; Taste Buds - metabolism; TRPM Cation Channels; Type C Phospholipases - deficiency; Type C Phospholipases - genetics
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/S0092-8674(03)00071-0

Mammals can taste a wide repertoire of chemosensory stimuli. Two unrelated families of receptors (T1Rs and T2Rs) mediate responses to sweet, amino acids, and bitter compounds. Here, we demonstrate that knockouts of TRPM5, a taste TRP ion channel, or PLCβ2, a phospholipase C selectively expressed in taste tissue, abolish sweet, amino acid, and bitter taste reception, but do not impact sour or salty tastes. Therefore, despite relying on different receptors, sweet, amino acid, and bitter transduction converge on common signaling molecules. Using PLCβ2 taste-blind animals, we then examined a fundamental question in taste perception: how taste modalities are encoded at the cellular level. Mice engineered to rescue PLCβ2 function exclusively in bitter-receptor expressing cells respond normally to bitter tastants but do not taste sweet or amino acid stimuli. Thus, bitter is encoded independently of sweet and amino acids, and taste receptor cells are not broadly tuned across these modalities.