Journal of Biological Chemistry
Volume 280, Issue 16, 22 April 2005, Pages 16254-16262
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Mechanisms of Signal Transduction
A Novel Chloride Channel in Drosophila melanogaster Is Inhibited by Protons*

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A systematic analysis of the Drosophila genome data reveals the existence of pHCl, a novel member of ligand-gated ion channel subunits. pHCl shows nearly identical similarity to glutamate-, glycine-, and histamine-gated ion channels, does however not belong to any of these ion channel types. We identified three different sites, where splicing generates multiple transcripts of the pHCl mRNA. The pHCl is expressed in Drosophila embryo, larvae, pupae, and the adult fly. In embryos, in situ hybridization detected pHCl in the neural cord and the hindgut. Functional expression of the three different splice variants of pHCl in oocytes of Xenopus laevis and Sf9 cells induces a chloride current with a linear current-voltage relationship that is inhibited by extracellular protons and activated by avermectins in a pH-dependent manner. Further, currents through pHCl channels were induced by a raise in temperature. Our data give genetic and electrophysiological evidence that pHCl is a member of a new branch of ligand-gated ion channels in invertebrates with, however, a hitherto unique combination of pharmacological and biophysical properties.

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Both authors contributed equally to this work.

*

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank/EBI Data Bank with accession number(s) AY880248, AY880249, and AY880250.