What is it about?

This study is about the detection of the enzymatic activity of cyclic AMP-dependent kinase (PKA) in the retina using a transgenic fluorescent mouse PKAchu. Thorough microscopic observation and analysis from live retinal explant identified that only rod photoreceptor cells show the ability to activate PKA in darkness after intense light stimulation.

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Why is it important?

Rod PKA activation was detected for about 15 min after brief 6 sec light stimulation. Previous biochemical and physiological studies suggested the role of PKA to boost the rod visual sensitivity in darkness. This study further added the insight that rod PKA is activated at appropriate timing when the light environment is changed.


This study gives the lines of evidence indicating that PKA is driven under rhodopsin, a light sensor protein in rod photoreceptor cells. The conventional rhodopsin pathway can be driven even with feeble light and leads to cyclic GMP degradation through the cascade of activation of enzymes called transducin (Gt) and phosphodiesterase (PDE). However, the paper suggests that rhodopsin activates cyclic AMP-dependent kinase only with strong light. The link between rhodopsin and cyclic AMP is still unknown, and future studies will address the molecular mechanism for it.

Shinya Sato
Kyoto Daigaku

Read the Original

This page is a summary of: Rhodopsin-mediated light-off-induced protein kinase A activation in mouse rod photoreceptor cells, Proceedings of the National Academy of Sciences, October 2020, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2009164117.
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