Addition of human melanopsin renders mammalian cells photoresponsive

Research output: Contribution to journalArticlepeer-review

  • Authors:
  • Z. Melyan
  • E. E. Tarttelin
  • J. Bellingham
  • R. J. Lucas
  • M. W. Hankins


A small number of mammalian retinal ganglion cells act as photoreceptors for regulating certain non-image forming photoresponses. These intrinsically photosensitive retinal ganglion cells express the putative photopigment melanopsin. Ablation of the melanopsin gene renders these cells insensitive to light; however, the precise role of melanopsin in supporting cellular photosensitivity is unconfirmed. Here we show that heterologous expression of human melanopsin in a mouse paraneuronal cell line (Neuro-2a) is sufficient to render these cells photoreceptive. Under such conditions, melanopsin acts as a sensory photopigment, coupled to a native ion channel via a G-protein signalling cascade, to drive physiological light detection. The melanopsin photoresponse relies on the presence of cis-isoforms of retinaldehyde and is selectively sensitive to short-wavelength light. We also present evidence to show that melanopsin functions as a bistable pigment in this system, having an intrinsic photoisomerase regeneration function that is chromatically shifted to longer wavelengths.

Bibliographical metadata

Original languageEnglish
Pages (from-to)741-745
Number of pages4
Issue number7027
Publication statusPublished - 17 Feb 2005

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