Melanopsin is a G protein-coupled receptor with a peak sensitivity in the blue part of the spectrum, which plays a key role in nonvisual light-mediated signaling. Recently, its importance in forming visual pathway as well as its role in blood vessels photorelaxation was also revealed. Melanopsin was discovered in 1998 in Xenopus leavis. Since then, the melanopsin presence was demonstrated across the species. The existence of two melanopsin genes (opn4m and opn4x) as well as melanopsin isoforms resulting from alternative splicing contributes to the variety in melanopsin-regulated processes. In this review, the diversity in melanopsin-induced signaling, regulation of melanopsin activity by phosphorylation and regulation of melanopsin mRNA are discussed.
© 2018 The American Society of Photobiology.