TRPM3 [TRP (transient receptor potential) melastatin 3] is one of the least investigated proteins of the TRP family of ion channels. Heterologously expressed TRPM3 channels are constitutively active, have an outwardly rectifying current–voltage relationship and are inhibited by intracellular Mg2+ ions. Besides these rather common features, in which TRPM3 channels resemble the closely related channels TRPM6 and TRPM7, TRPM3 channels have several unique characteristics. The TRPM3 gene encodes a plethora of different proteins owing to alternative splicing and alternative exon usage. One site of alternative splicing affects the ion-conducting pore region and profoundly alters the pore properties of the encoded channels. The channels having the longer pore region efficiently conduct univalent cations, but are only poorly permeated by bivalent cations. Conversely, the channels with the shorter pore region are highly permeable to bivalent cations. Unusually, the short-pore TRPM3 channels are inhibited by extracellular Na+ ions. At physiological sodium concentration, this block is very strong, making it difficult to envision a physiological function for these ion channels. Recently, pharmacological investigations have been initiated in order to identify substances that influence TRPM3 channel activity. With the use of such substances, it might be possible to identify TRPM3 channels in their native environment and to elucidate some of their physiological roles. Hopefully, TRPM3 channels will then no longer appear to be as enigmatic as they do right now.
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February 2007
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Conference Article|
January 22 2007
TRPM3, a biophysical enigma?
J. Oberwinkler
J. Oberwinkler
1
1Institut für Pharmakologie und Toxikologie, Gebäude 46, Universitätsklinikum des Saarlandes, 66421 Homburg, Germany
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Publisher: Portland Press Ltd
Received:
November 14 2006
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2007 The Biochemical Society
2007
Biochem Soc Trans (2007) 35 (1): 89–90.
Article history
Received:
November 14 2006
Citation
J. Oberwinkler; TRPM3, a biophysical enigma?. Biochem Soc Trans 1 February 2007; 35 (1): 89–90. doi: https://doi.org/10.1042/BST0350089
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