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.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Choice Behavior / physiology
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Female
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GTP-Binding Protein alpha Subunits / metabolism
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GTP-Binding Protein beta Subunits / genetics*
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GTP-Binding Protein beta Subunits / metabolism
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GTP-Binding Protein beta Subunits / physiology*
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GTP-Binding Protein gamma Subunits / genetics*
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GTP-Binding Protein gamma Subunits / metabolism
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GTP-Binding Protein gamma Subunits / physiology*
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Male
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Mice
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Mice, Knockout
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Models, Statistical*
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Night Vision / genetics
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Night Vision / physiology*
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Photic Stimulation
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Retina / anatomy & histology
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Retina / metabolism
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Retina / physiology
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Retina / ultrastructure
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Retinal Rod Photoreceptor Cells / metabolism
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Retinal Rod Photoreceptor Cells / physiology*
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Signal Transduction / genetics
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Signal Transduction / physiology*
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Transducin / metabolism
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Vision, Ocular / genetics
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Vision, Ocular / physiology*
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Visual Perception / genetics
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Visual Perception / physiology*
Substances
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G-protein Beta gamma
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GTP-Binding Protein alpha Subunits
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GTP-Binding Protein beta Subunits
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GTP-Binding Protein gamma Subunits
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Transducin