Melanopsin: An opsin in melanophores, brain, and eye

Proc Natl Acad Sci U S A. 1998 Jan 6;95(1):340-5. doi: 10.1073/pnas.95.1.340.


We have identified an opsin, melanopsin, in photosensitive dermal melanophores of Xenopus laevis. Its deduced amino acid sequence shares greatest homology with cephalopod opsins. The predicted secondary structure of melanopsin indicates the presence of a long cytoplasmic tail with multiple putative phosphorylation sites, suggesting that this opsin's function may be finely regulated. Melanopsin mRNA is expressed in hypothalamic sites thought to contain deep brain photoreceptors and in the iris, a structure known to be directly photosensitive in amphibians. Melanopsin message is also localized in retinal cells residing in the outermost lamina of the inner nuclear layer where horizontal cells are typically found. Its expression in retinal and nonretinal tissues suggests a role in vision and nonvisual photoreceptive tasks, such as photic control of skin pigmentation, pupillary aperture, and circadian and photoperiodic physiology.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Brain Chemistry*
  • Cells, Cultured
  • DNA, Complementary / chemistry
  • Eye / chemistry*
  • In Situ Hybridization
  • Melanophores / chemistry*
  • Molecular Sequence Data
  • Protein Structure, Secondary
  • Rod Opsins / analysis
  • Rod Opsins / chemistry*
  • Rod Opsins / genetics
  • Sequence Alignment
  • Xenopus laevis


  • DNA, Complementary
  • Rod Opsins
  • melanopsin

Associated data

  • GENBANK/AF014797