Referenced in: none

Automatically associated channels: Slo1

Title: Arrestin translocation is stoichiometric to rhodopsin isomerization and accelerated by phototransduction in Drosophila photoreceptors.

Authors: Akiko K Satoh, Hongai Xia, Limin Yan, Che-Hsiung Liu, Roger C Hardie, Donald F Ready

Journal, date & volume: Neuron, 2010 Sep 23 , 67, 997-1008

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/20869596

Abstract
Upon illumination, visual arrestin translocates from photoreceptor cell bodies to rhodopsin and membrane-rich photosensory compartments, vertebrate outer segments or invertebrate rhabdomeres, where it quenches activated rhodopsin. Both the mechanism and function of arrestin translocation are unresolved and controversial. In dark-adapted photoreceptors of the fruitfly Drosophila, confocal immunocytochemistry shows arrestin (Arr2) associated with distributed photoreceptor endomembranes. Immunocytochemistry and live imaging of GFP-tagged Arr2 demonstrate rapid reversible translocation to stimulated rhabdomeres in stoichiometric proportion to rhodopsin photoisomerization. Translocation is very rapid in normal photoreceptors (time constant <10 s) and can also be resolved in the time course of electroretinogram recordings. Genetic elimination of key phototransduction proteins, including phospholipase C (PLC), Gq, and the light-sensitive Ca2+-permeable TRP channels, slows translocation by 10- to 100-fold. Our results indicate that Arr2 translocation in Drosophila photoreceptors is driven by diffusion, but profoundly accelerated by phototransduction and Ca2+ influx.