Making sense with TRP channels: store-operated calcium entry and the ion channel Trpm5 in taste receptor cells.
The sense of taste plays a critical role in the life and nutritional status of organisms. During the last decade, several molecules involved in taste detection and transduction have been identified, providing a better understanding of the molecular physiology of taste receptor cells. However, a comprehensive catalogue of the taste receptor cell signaling machinery is still unavailable. We have recently described the occurrence of calcium signaling mechanisms in taste receptor cells via apparent store-operated channels and identified Trpm5, a novel candidate taste transduction element belonging to the mammalian family of transient receptor potential channels. Trpm5 is expressed in a tissue-restricted manner, with high levels in gustatory tissue. In taste cells, Trpm5 is co-expressed with taste-signaling molecules such as alpha-gustducin, Ggamma(13), phospholipase C beta(2) and inositol 1,4,5-trisphosphate receptor type III. Biophysical studies of Trpm5 heterologously expressed in Xenopus oocytes and mammalian CHO-K1 cells indicate that it functions as a store-operated channel that mediates capacitative calcium entry. The role of store-operated channels and Trpm5 in capacitative calcium entry in taste receptor cells in response to bitter compounds is discussed.
Pérez
Cristian A
CA
Department of Physiology & Biophysics, Howard Hughes Medical Institute, Mount Sinai School of Medicine, New York University, New York, NY 10029, USA. Cristian.Perez@rockefeller.edu
Margolskee
Robert F
RF
Kinnamon
Sue C
SC
Ogura
Tatsuya
T
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008565:Membrane Proteins / Q000502:physiology*; D054799:Phospholipase C beta; D011984:Sensory Receptor Cells / Q000502:physiology*; D050052:TRPC Cation Channels; D050053:TRPM Cation Channels; D013650:Taste Buds / Q000502:physiology*; D010738:Type C Phospholipases / Q000378:metabolism
D015220:Calcium Channels; D007527:Isoenzymes; D008565:Membrane Proteins; D050052:TRPC Cation Channels; D050053:TRPM Cation Channels; C404409:TRPM5 protein, human; D010738:Type C Phospholipases; C518036:PLCB2 protein, human; D054799:Phospholipase C beta; D002118:Calcium