G-Protein βγ-Complex Is Crucial for Efficient Signal Amplification in Vision

• Published in: The Journal of neuroscience 2011-06, Vol.31 (22), p.8067-8077
• Main Authors: Kolesnikov, Alexander V., Rikimaru, Loryn, Hennig, Anne K., Lukasiewicz, Peter D., Fliesler, Steven J., Govardovskii, Victor I., Kefalov, Vladimir J., Kisselev, Oleg G.
• Format: Article
• Language: English
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/JNEUROSCI.0174-11.2011

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.