Opn5L1 is a retinal receptor that behaves as a reverse and self-regenerating photoreceptor

Nat Commun. 2018 Mar 28;9(1):1255. doi: 10.1038/s41467-018-03603-3.


Most opsins are G protein-coupled receptors that utilize retinal both as a ligand and as a chromophore. Opsins' main established mechanism is light-triggered activation through retinal 11-cis-to-all-trans photoisomerization. Here we report a vertebrate non-visual opsin that functions as a Gi-coupled retinal receptor that is deactivated by light and can thermally self-regenerate. This opsin, Opn5L1, binds exclusively to all-trans-retinal. More interestingly, the light-induced deactivation through retinal trans-to-cis isomerization is followed by formation of a covalent adduct between retinal and a nearby cysteine, which breaks the retinal-conjugated double bond system, probably at the C11 position, resulting in thermal re-isomerization to all-trans-retinal. Thus, Opn5L1 acts as a reverse photoreceptor. We conclude that, like vertebrate rhodopsin, Opn5L1 is a unidirectional optical switch optimized from an ancestral bidirectional optical switch, such as invertebrate rhodopsin, to increase the S/N ratio of the signal transduction, although the direction of optimization is opposite to that of vertebrate rhodopsin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chickens
  • Chromatography, High Pressure Liquid
  • Factor Xa / chemistry
  • HEK293 Cells
  • Humans
  • In Situ Hybridization
  • Light
  • Male
  • Opsins / chemistry*
  • Photoreceptor Cells
  • Photoreceptor Cells, Vertebrate / chemistry*
  • Protein Binding
  • Recombinant Proteins / chemistry
  • Regeneration
  • Retinaldehyde / metabolism
  • Rhodopsin / chemistry
  • Signal Transduction
  • Vitamin A / chemistry
  • Xenopus / metabolism


  • Opsins
  • Recombinant Proteins
  • Vitamin A
  • Rhodopsin
  • Factor Xa
  • Retinaldehyde