C-terminal phosphorylation regulates the kinetics of a subset of melanopsin-mediated behaviors in mice

C-terminal phosphorylation of melanopsin significantly influences the recovery kinetics of the intrinsic photoresponse in retinal cells.

• C-terminal phosphorylation determines the duration of the pupillary light reflex (PLR) and the speed of reentrainment to light/dark cycles.
• A melanopsin variant without C-terminal phosphorylation sites leads to a prolonged intrinsic light response in intrinsically photosensitive retinal ganglion cells (ipRGCs).
• Mice with the C-terminal phosphonull variant reentrain faster to a delayed light/dark cycle compared to those with wild-type melanopsin.
• The phosphonull variant shows a sustained PLR only at brighter light intensities that activate melanopsin, not at dimmer levels activating the rod/cone pathway.
• Circadian phase alignment and direct light effects on activity are not affected by C-terminal phosphorylation of melanopsin.

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