Control of rhodopsin's active lifetime by arrestin-1 expression in mammalian rods.
In rod photoreceptors, deactivation of the light-activated G-protein-coupled receptor rhodopsin (R*) is initiated by phosphorylation and completed through subsequent binding of visual arrestin (Arr1). The in vivo kinetics of these individual interactions have proven difficult to determine with precision since R* lifetime is much shorter than the lifetimes of downstream G-protein and effector molecules. Here, we have used a transgenic mouse line with accelerated downstream deactivation kinetics to reveal the contribution of Arr1 binding to the overall time course of rhodopsin deactivation. Photoresponses revealed that the lifetime of R* is significantly increased in rods that express half of the normal amount of Arr1, in a manner consistent with a twofold decrease in the rate of Arr1 binding across a wide range of flash strengths. A basic model of photoresponse deactivation consistent with established photoreceptor biochemistry shows that R* phosphorylation and Arr1 binding occur with a time constant of approximately 40 ms in wild-type mouse rods, much faster than previous estimates.
Gross
Owen P
OP
Department of Ophthalmology & Vision Science, Center for Neuroscience, University of California, Davis, Davis, California 95618, USA.
Burns
Marie E
ME
D000818:Animals; D019393:Arrestin / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics / Q000528:radiation effects; D007700:Kinetics; D008027:Light; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D010766:Phosphorylation / Q000528:radiation effects; D010775:Photic Stimulation; D010777:Photochemistry; D011485:Protein Binding / Q000235:genetics; D011930:Reaction Time / Q000235:genetics / Q000528:radiation effects; D012160:Retina / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects; D012243:Rhodopsin / Q000378:metabolism*; D013997:Time Factors; D014785:Vision, Ocular / Q000235:genetics* / Q000528:radiation effects
D019393:Arrestin; D012243:Rhodopsin