title: Mouse cones require an arrestin for normal inactivation of phototransduction.
abstract: Arrestins are proteins that arrest the activity of G protein-coupled receptors (GPCRs). While it is well established that normal inactivation of photoexcited rhodopsin, the GPCR of rod phototransduction, requires arrestin (Arr1), it has been controversial whether the same requirement holds for cone opsin inactivation. Mouse cone photoreceptors express two distinct visual arrestins: Arr1 and Arr4. By means of recordings from cones of mice with one or both arrestins knocked out, this investigation establishes that a visual arrestin is required for normal cone inactivation. Arrestin-independent inactivation is 70-fold more rapid in cones than in rods, however. Dual arrestin expression in cones could be a holdover from ancient genome duplication events that led to multiple isoforms of arrestin, allowing evolutionary specialization of one form while the other maintains the basic function.
authors.affiliation: F.M. Kirby Center for Molecular Ophthalmology, Department of Ophthalmology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6069, USA.
authors.forename: Sergei S
authors.initials: SS
authors.lastname: Nikonov
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Brown
authors.forename: Jason A
authors.initials: JA
authors.lastname: Davis
authors.forename: Freddi I
authors.initials: FI
authors.lastname: Zuniga
authors.forename: Alvina
authors.initials: A
authors.lastname: Bragin
authors.forename: Edward N
authors.initials: EN
authors.lastname: Pugh
authors.forename: Cheryl M
authors.initials: CM
authors.lastname: Craft
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D019393:Arrestin / Q000145:classification / Q000172:deficiency / Q000378:metabolism*; D004594:Electrophysiology; D008027:Light; D008564:Membrane Potentials / Q000235:genetics / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D011930:Reaction Time / Q000502:physiology; D012160:Retina / Q000166:cytology; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D017299:Rod Opsins / Q000494:pharmacology; D014785:Vision, Ocular / Q000502:physiology* / Q000528:radiation effects
chemical_list: D019393:Arrestin; D017299:Rod Opsins