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XB-ART-55571
Nat Commun January 1, 2018; 9 (1): 1255.
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Opn5L1 is a retinal receptor that behaves as a reverse and self-regenerating photoreceptor.

Sato K , Yamashita T , Ohuchi H , Takeuchi A , Gotoh H , Ono K , Mizuno M , Mizutani Y , Tomonari S , Sakai K , Imamoto Y , Wada A , Shichida Y .


Abstract
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.

PubMed ID: 29593298
PMC ID: PMC5871776
Article link: Nat Commun


Species referenced: Xenopus
Genes referenced: opn5 prl.2 rho rpe zic1


Article Images: [+] show captions
References [+] :
Ablonczy, 11-cis-retinal reduces constitutive opsin phosphorylation and improves quantum catch in retinoid-deficient mouse rod photoreceptors. 2002, Pubmed