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Role of Protein Phosphatase 2A in Regulating the Visual Signaling in Drosophila
Author(s) -
Shieh BihHwa,
Wang Ning,
Leung HungTat,
Pak William L
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.2_supplement.315
Subject(s) - dephosphorylation , phosphorylation , protein phosphatase 2 , phosphatase , microbiology and biotechnology , protein kinase c , in vivo , visual phototransduction , kinase , protein subunit , biology , chemistry , biophysics , biochemistry , genetics , gene , retinal
Drosophila visual signaling, a G‐protein coupled PLCbeta4‐mediated mechanism, is regulated by eye‐PKC that promotes light adaptation and fast deactivation, most likely via phosphorylation of INAD and TRP. To reveal the critical phosphatases that dephosphorylate INAD, we utilized several biochemical analyses and identified PP2A as a candidate. Importantly, the catalytic subunit of PP2A, MTS, is co‐purified with INAD, and an elevated phosphorylation of INAD by eye‐PKC was observed in three mts heterozygotes. To explore whether PP2A (MTS) regulates dephosphorylation of INAD by counteracting eye‐PKC (INAC) in vivo, we performed ERG recordings. We discover that inaCP209 is semi‐dominant, because inaCP209 heterozygotes display abnormal light adaptation and slow deactivation. Interestingly, the deactivation defect of inaCP209 heterozygotes was rescued by the mtsXE2258 heterozygous background. In contrast, mtsXE2258 failed to modify the severe deactivation of norpAP16, indicating that MTS does not modulate NORPA (PLCbeta4). Together, our results strongly indicate that dephosphorylation of INAD is catalyzed by PP2A, and a reduction of PP2A can compensate for a partial loss of function in eye‐PKC restoring the fast deactivation kinetics in vivo. We thus propose that the fast deactivation of the visual response is modulated in part by the phosphorylation of INAD.