Channel Candidates

By Kerry Grens

While many potential mechanotransduction channels have been disregarded outright, a few have proved promising and others still remain a possibility. here are a few of the likeliest candidates, past and present. Those that remain a possibility are marked with an asterisk (*).

CHANNEL	EVIDENCE FOR	EVIDENCE AGAINST	REFERENCES
Nompc, transient receptor potential (TRP) channel in Drosophila	Mutants have vestibular defects and altered transduction current	NompC gene is not present in mammals	Science, 287:2229-34, 2000
TRPA1, mammalian TRP channel	Antibody to channel localizes to stereocilia tips, and inhibition of the channel alters transduction current	Knockout mice have no hearing disabilities	Nature, 432:723-30, 2004
ENaC, family of amiloridesensitive epithelial sodium channels	C. elegans mutants are defective for mechanosensation; protein localized to hair cell stereocilia; also present in sensory endings in skin	Conductance too low; knockout mice have normal hearing	J Physiol-London, 558:659-69, 2004
TRPML3*, mammalian TRP channel	Mutant mice are born deaf; gene expressed in hair cells	No physiologic evidence to support channel's role in transduction	PNAS, 99:14994-9, 2002
TRPP*, mammalian channel; responsible for polycystic kidney disease	Involved in mechanosensation in kidney epithelial cells; conductance comparable to mechanotransduction channel	Unknown whether hair cells express channel	J Neurosci, 26:10992-1000, 2006