Calmodulin regulation of Drosophila light-activated channels and receptor function mediates termination of the light response in vivo.
Calmodulin (CAM) participates in a variety of intracellular transduction processes by modulating signaling molecules in response to calcium changes. We report the characterization of Drosophila Cam mutants and the role of CAM in photoreceptor cell function. Contrary to current models of excitation and TRP channel function, we demonstrate that the transient phenotype of trp mutants can be explained by CAM regulation of the TRPL channel rather than by the loss of a store-operated conductance leading to depletion of the internal stores. We also analyzed light responses in a variety of mutant and transgenic backgrounds and demonstrate the importance of calmodulin in mediating calcium-dependent negative regulation of phototransduction. Our results show that CAM coordinates termination of the light response by modulating receptor and ion channel activity.
Scott
K
K
Howard Hughes Medical Institute, Department of Biology, University of California at San Diego, La Jolla 92093-0649, USA.
Sun
Y
Y
Beckingham
K
K
Zuker
C S
CS
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D007473:Ion Channels / Q000378:metabolism*; D008027:Light; D008565:Membrane Proteins / Q000378:metabolism*; D009154:Mutation; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism*; D012243:Rhodopsin / Q000378:metabolism; D050051:Transient Receptor Potential Channels; D014785:Vision, Ocular
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D029721:Drosophila Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D050051:Transient Receptor Potential Channels; C074192:trpl protein, Drosophila; D012243:Rhodopsin; D002118:Calcium