The SOCS box protein STOPS is required for phototransduction through its effects on phospholipase C.
Phosphoinositide-specific phospholipase C (PLC) isozymes play roles in a diversity of processes including Drosophila phototransduction. In fly photoreceptor cells, the PLCbeta encoded by norpA is critical for activation of TRP channels. Here, we describe a PLCbeta regulator, STOPS, which encodes a SOCS box protein. Mutation of stops resulted in a reduced concentration of NORPA and a defect in stopping signaling following cessation of the light stimulus. NORPA has been proposed to have dual roles as a PLC- and GTPase-activating protein (GAP). We found that the slow termination resulting from expressing low levels of wild-type NORPA was suppressed by addition of normal amounts of an altered NORPA, which had wild-type GAP activity, but no PLC activity. STOPS is the first protein identified that specifically regulates PLCbeta protein concentration. Moreover, this work demonstrates that a PLCbeta derivative that does not promote TRP channel activation, still contributes to signaling in vivo.
Wang
Tao
T
Department of Biological Chemistry, Center for Sensory Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Wang
Xiaoyue
X
Xie
Qiang
Q
Montell
Craig
C
D000818:Animals; D030801:Animals, Genetically Modified; D017920:Antiporters / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics; D004331:Drosophila melanogaster; D004596:Electroretinography / Q000379:methods; D020558:GTP Phosphohydrolases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology* / Q000528:radiation effects; D006358:Hot Temperature; D008564:Membrane Potentials / Q000502:physiology / Q000528:radiation effects; D008869:Microtubule-Associated Proteins / Q000502:physiology*; D009154:Mutation / Q000502:physiology; D054799:Phospholipase C beta / Q000235:genetics; D010775:Photic Stimulation / Q000379:methods; D010786:Photoreceptor Cells / Q000502:physiology; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology / Q000528:radiation effects; D017434:Protein Structure, Tertiary / Q000502:physiology; D016415:Sequence Alignment; D050826:Suppressor of Cytokine Signaling Proteins / Q000737:chemistry / Q000502:physiology*; D010738:Type C Phospholipases / Q000378:metabolism*; D014785:Vision, Ocular / Q000502:physiology*
D017920:Antiporters; C108396:Calx protein, Drosophila; D029721:Drosophila Proteins; D008869:Microtubule-Associated Proteins; D050826:Suppressor of Cytokine Signaling Proteins; D010738:Type C Phospholipases; C468371:NorpA protein, Drosophila; D054799:Phospholipase C beta; D020558:GTP Phosphohydrolases