The Drosophila light-activated conductance is composed of the two channels TRP and TRPL.
Drosophila phototransduction is a G protein-coupled, calcium-regulated signaling cascade that serves as a model system for the dissection of phospholipase C (PLC) signaling in vivo. The Drosophila light-activated conductance is constituted in part by the transient receptor potential (trp) ion channel, yet trp mutants still display a robust response demonstrating the presence of additional channels. The transient receptor potential-like (trpl) gene encodes a protein displaying 40% amino acid identity with TRP. Mammalian homologs of TRP and TRPL recently have been isolated and postulated to encode components of the elusive I(crac) conductance. We now show that TRP and TRPL localize to the membrane of the transducing organelle, together with rhodopsin and PLC, consistent with a role in PLC signaling during phototransduction. To determine the function of TRPL in vivo, we isolated trpl mutants and characterized them physiologically and genetically. We demonstrate that the light-activated conductance is composed of TRP and TRPL ion channels and that each can be activated on its own. We also use genetic and electrophysiological tools to study the contribution of each channel type to the light response and show that TRP and TRPL can serve partially overlapping functions.
Niemeyer
B A
BA
Howard Hughes Medical Institute, Department of Biology, Department of Neurosciences, University of California at San Diego, La Jolla, California 92093-0649, USA.
Suzuki
E
E
Scott
K
K
Jalink
K
K
Zuker
C S
CS
D000595:Amino Acid Sequence; D000818:Animals; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D004330:Drosophila / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029721:Drosophila Proteins; D005260:Female; D007301:Insect Hormones / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D019476:Insect Proteins; D008027:Light; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D008969:Molecular Sequence Data; D009154:Mutation; D018462:Photobiology; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism / Q000528:radiation effects; D015398:Signal Transduction; D050051:Transient Receptor Potential Channels
D015220:Calcium Channels; D002148:Calmodulin-Binding Proteins; D029721:Drosophila Proteins; D007301:Insect Hormones; D019476:Insect Proteins; D008565:Membrane Proteins; D050051:Transient Receptor Potential Channels; C063169:trp protein, Drosophila; C074192:trpl protein, Drosophila