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An evolutionarily conserved gene family encodes proton-selective ion channels

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Science  02 Mar 2018:
Vol. 359, Issue 6379, pp. 1047-1050
DOI: 10.1126/science.aao3264

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The proton channel behind sour taste

Although many proteins that form ion channels in cell membranes have been described, none that selectively conduct protons into eukaryotic cells have been identified. Tu et al. used a genetic screen to pinpoint candidate genes that might encode such a protein from mouse taste receptor cells (see the Perspective by Montell). They identified the known protein otopetrin and showed that it conferred proton conductance when expressed in cultured human cells. Their results indicate that otopetrin may function in sensory recognition of sour (acidic) taste in humans and other organisms.

Science, this issue p. 1047; see also p. 991

Abstract

Ion channels form the basis for cellular electrical signaling. Despite the scores of genetically identified ion channels selective for other monatomic ions, only one type of proton-selective ion channel has been found in eukaryotic cells. By comparative transcriptome analysis of mouse taste receptor cells, we identified Otopetrin1 (OTOP1), a protein required for development of gravity-sensing otoconia in the vestibular system, as forming a proton-selective ion channel. We found that murine OTOP1 is enriched in acid-detecting taste receptor cells and is required for their zinc-sensitive proton conductance. Two related murine genes, Otop2 and Otop3, and a Drosophila ortholog also encode proton channels. Evolutionary conservation of the gene family and its widespread tissue distribution suggest a broad role for proton channels in physiology and pathophysiology.

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