title: Light-induced translocation of Drosophila visual Arrestin2 depends on Rac2.
abstract: Photoreceptor cells are remarkable in their ability to adjust their sensitivity to light over a wide range of intensities. Rapid termination of the photoresponse is achieved in part by shuttling proteins in and out of the light-transducing compartment of the photoreceptor cells. One protein that undergoes light-dependent translocation is the rhodopsin regulatory protein arrestin. However, the mechanisms coupling rhodopsin to arrestin movement are poorly understood. Here we show that light-dependent shuttling of the major arrestin in Drosophila photoreceptor cells, Arrestin2 (Arr2), occurs independently of known elements of the phototransduction cascade. Disruptions of the trimeric G protein, phospholipase Cbeta, the TRP channel, or the Na(+)/Ca(2+) exchanger did not influence Arr2 localization. Rather, we found that loss of the small GTPase Rac2 severely impaired Arr2 movement and prolonged the termination of the photoresponse. Our findings demonstrate that light-induced translocation of Arr2 occurs through a noncanonical rhodopsin/Rac2 pathway, which is distinct from the classical phototransduction cascade.
authors.affiliation: Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Center for Sensory Biology, Baltimore, MD 21205, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Elsaesser
authors.forename: Deepak
authors.initials: D
authors.lastname: Kalra
authors.forename: Ruoxia
authors.initials: R
authors.lastname: Li
authors.forename: Craig
authors.initials: C
authors.lastname: Montell
mesh_terms: D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D008027:Light; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism / Q000528:radiation effects / Q000648:ultrastructure; D021381:Protein Transport / Q000528:radiation effects; D012243:Rhodopsin; D014785:Vision, Ocular / Q000528:radiation effects; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000097766:RAC2 GTP-Binding Protein
chemical_list: D019390:Arrestins; D029721:Drosophila Proteins; D005136:Eye Proteins; D012243:Rhodopsin; D020744:rac GTP-Binding Proteins; D000097766:RAC2 GTP-Binding Protein; C504666:Arr2 protein, Drosophila; C083315:ninaE protein, Drosophila