Light-dependent phosphorylation of the Drosophila transient receptor potential (TRP) ion channel

Publikations-Art
Zeitschriftenbeitrag (peer-reviewed)
Autoren
Olaf Voolstra, Katherina Beck, Claudia Oberegelsbacher, Jens Pfannstiel, Armin Huber
Erscheinungsjahr
2010
Veröffentlicht in
J. Biol. Chem.
Herausgeber
The American Society for Biochemistry and Molecular Biology, Inc.
Band/Volume
285/19/
ISBN / ISSN / eISSN
ISSN 0021-9258
Seite (von - bis)
14275-14284
Abstract

The Drosophila phototransduction cascade terminates in the opening of an ion channel, designated "transient receptor potential", TRP . TRP has been shown to become phosphorylated in vitro, suggesting regulation of the ion channel through posttranslational modification. However, except for one phosphorylation site, S982, which was analyzed by functional in vivo studies (1), nothing is known about the role of TRP phosphorylation in vivo. Here, we report the identification of 21 TRP phosphorylation sites by a mass spectrometry approach. 20 phoshorylation sites are located in the C-terminal portion of the channel and one site is located near the N-terminus. All 21 phosphorylation sites were also identified in the inaCP209 mutant indicating that phosphorylation of TRP at these sites occurred independently from the eye-PKC. Relative quantification of phosphopeptides revealed that at least seven phosphorylation sites were predominantly phosphorylated in the light whereas one site, S936, was predominantly phosphorylated in the dark. We show that TRP phosphorylated at S936 was located in the rhabomere. Light-dependent changes in the phosphorylation state of this site occurred within minutes. The dephosphorylation of TRP at S936 required activation of the phototransduction cascade.

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