Phosphorylation of the transient receptor potential (TRP) ion channel in Drosophila vision

The visual transduction cascade in Drosophila melanogaster is one of the fastest known G protein-mediated signaling pathways that culminates in the opening of the transient receptor potential (TRP) channel that belongs to the large protein family of TRPC channels. Like many other ion channels, TRP becomes posttranslationally modified. We recently identified 21 phosphorylation sites of the Drosophila TRP channel. At least eight of these sites were phosphorylated in a light-dependent manner. The proposed project aims at elucidating the physiological role of the identified TRP phosphorylation sites. We will investigate the regulation of phosphorylation/dephosphorylation of individual sites and study correlation of the subcellular localization of the ion channels with their phosphorylation state. We wil abolish the identified phosphorylation sites by site-directed mutagenesis, express the mutated trp constructs in transgenic flies, and analyze the effects of the mutations. In order to identify kinases and phosphatases of the TRP protein, we will perform am LC-MS/MS approach along with a screen using candidate kinase and phosphatase mutants. The gained  insights should result in a bette understanding of the regulation of the widely distributed superfamily of TRP ion channels.

Sponsored by DFG, VO 1741/1-1