Independent anchoring and assembly mechanisms of INAD signaling complexes in Drosophila photoreceptors.
In Drosophila photoreceptors the multivalent PDZ protein INAD organizes the phototransduction cascade into a macromolecular signaling complex containing the effector PLC, the light-activated TRP channels, and a regulatory PKC. Previously, we showed that the subcellular localization of INAD signaling complexes is critical for signaling. Now we have examined how INAD complexes are anchored and assembled in photoreceptor cells. We find that trp mutants, or transgenic flies expressing inaD alleles that disrupt the interaction between INAD and TRP, cause the mislocalization of the entire transduction complex. The INAD-TRP interaction is not required for targeting but rather for anchoring of complexes, because INAD and TRP can be targeted independently of each other. We also show that, in addition to its scaffold role, INAD functions to preassemble transduction complexes. Preassembly of signaling complexes helps to ensure that transduction complexes with the appropriate composition end up in the proper location. This may be a general mechanism used by cells to target different signaling machinery to the pertinent subcellular location.
Tsunoda
S
S
Howard Hughes Medical Institute and Departments of Biology and Neurosciences, University of California at San Diego, La Jolla, California 92093-0649, USA. susan@flyeye.ucsd.edu
Sun
Y
Y
Suzuki
E
E
Zuker
C
C
D000818:Animals; D016466:CHO Cells; D015220:Calcium Channels / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D004330:Drosophila; D029721:Drosophila Proteins; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism* / Q000648:ultrastructure; D011233:Precipitin Tests; D011493:Protein Kinase C / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport / Q000235:genetics; D050052:TRPC Cation Channels; D010738:Type C Phospholipases / Q000378:metabolism; D014785:Vision, Ocular / Q000502:physiology*
D015220:Calcium Channels; D029721:Drosophila Proteins; D005136:Eye Proteins; D046911:Macromolecular Substances; D050052:TRPC Cation Channels; C091568:inaD protein, Drosophila; C096351:transient receptor potential cation channel, subfamily C, member 1; D011493:Protein Kinase C; D010738:Type C Phospholipases