Opn5L1 is a retinal receptor that behaves as a reverse and self-regenerating photoreceptor
NATURE COMMUNICATIONS(2018)
摘要
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 C 11 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.
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关键词
Biochemistry,G protein-coupled receptors,Science,Humanities and Social Sciences,multidisciplinary
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