title: G-protein betagamma-complex is crucial for efficient signal amplification in vision.
abstract: A fundamental question of cell signaling biology is how faint external signals produce robust physiological responses. One universal mechanism relies on signal amplification via intracellular cascades mediated by heterotrimeric G-proteins. This high amplification system allows retinal rod photoreceptors to detect single photons of light. Although much is now known about the role of the α-subunit of the rod-specific G-protein transducin in phototransduction, the physiological function of the auxiliary βγ-complex in this process remains a mystery. Here, we show that elimination of the transducin γ-subunit drastically reduces signal amplification in intact mouse rods. The consequence is a striking decline in rod visual sensitivity and severe impairment of nocturnal vision. Our findings demonstrate that transducin βγ-complex controls signal amplification of the rod phototransduction cascade and is critical for the ability of rod photoreceptors to function in low light conditions.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, Missouri 63110, USA.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Kolesnikov
authors.forename: Loryn
authors.initials: L
authors.lastname: Rikimaru
authors.forename: Anne K
authors.initials: AK
authors.lastname: Hennig
authors.forename: Peter D
authors.initials: PD
authors.lastname: Lukasiewicz
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Fliesler
authors.forename: Victor I
authors.initials: VI
authors.lastname: Govardovskii
authors.forename: Vladimir J
authors.initials: VJ
authors.lastname: Kefalov
authors.forename: Oleg G
authors.initials: OG
authors.lastname: Kisselev
mesh_terms: D000818:Animals; D002755:Choice Behavior / Q000502:physiology; D005260:Female; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism; D044387:GTP-Binding Protein beta Subunits / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D044388:GTP-Binding Protein gamma Subunits / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D015233:Models, Statistical; D055254:Night Vision / Q000235:genetics / Q000502:physiology*; D010775:Photic Stimulation; D012160:Retina / Q000033:anatomy & histology / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D017948:Retinal Rod Photoreceptor Cells / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D015293:Transducin / Q000378:metabolism; D014785:Vision, Ocular / Q000235:genetics / Q000502:physiology*; D014796:Visual Perception / Q000235:genetics / Q000502:physiology*
chemical_list: C118981:G-protein Beta gamma; D044385:GTP-Binding Protein alpha Subunits; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D015293:Transducin