Light‐activated phosphorylation of cephalopod rhodopsin

Light-dependent phosphorylation of rhodopsin (Rho) is a first step in the desensitization of the signaling state of the receptor during vertebrate and invertebrate visual transduction. We found that only 358Ser of the photoactivated octopus Rho (oRho*) was phosphorylated by octopus rhodopsin kinase (oRK). Tryptic truncation of the C-terminal PPQGY repeats of oRho that follow the phosphorylation region did not influence spectral or G-protein activation properties of oRho but abolished phosphorylation. Despite significant structural differences between oRK and mammalian RK, these results provide further evidence of the importance of singly phosphorylated species of Rho* in the generation of arrestin binding sites.

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“…Similar to vertebrate Rho, oRho undergoes light-dependent phosphorylation (20). As shown in this study, only 358Ser of oRho* is phosphorylated.…”

Section: Discussionsupporting

confidence: 66%

Identification of a Single Phosphorylation Site Within Octopus Rhodopsin

et al. 1998

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“…In microvillar photoreceptors rhodopsin also becomes phosphorylated after illumination (Paulsen and Hoppe, 1978;Vandenberg and Montal, 1984;Bentrop and Paulsen, 1986;Byk et al, 1993), and a rhodopsin kinase has been isolated from octopus (Kikkawa et al, 1998) squid (Mayeenuddin and Mitchell, 2001) and Drosophila (Doza et al, 1992;Lee et al, 2004). However, the role of rhodopsin phosphorylation in shaping the interaction with arrestin seemingly diverges from rods and cones.…”

Section: Discussionmentioning

confidence: 99%

Arrestin in Ciliary Invertebrate Photoreceptors: Molecular Identification and Functional AnalysisIn Vivo

Gómez¹,

Espinosa²,

Ramírez³

et al. 2011

J. Neurosci.

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Arrestin was identified in ciliary photoreceptors of Pecten irradians, and its role in terminating the light response was established electrophysiologically. Downstream effectors in these unusual visual cells diverge from both microvillar photoreceptors and rods and cones; the finding that key regulatory mechanisms of the early steps of visual excitation are conserved across such distant lineages of photoreceptors underscores that a common blueprint for phototransduction exists across metazoa. Arrestin was detected by Western blot analysis of retinal lysates, and localized in ciliary photoreceptors by immunostaining of whole-eye cryosections and dissociated cells. Two arrestin isoforms were molecularly identified by PCR; these present the canonical N-and C-arrestin domains, and are identical at the nucleotide level over much of their sequence. A high degree of homology to various ␤-arrestins (up to 70% amino acid identity) was found. In situ hybridization localized the two transcripts within the retina, but failed to reveal finer spatial segregation, possibly because of insufficient differences between the riboprobes. Intracellular dialysis of anti arrestin antibodies into voltage-clamped ciliary photoreceptors produced a gradual slow-down of the photocurrent falling phase, leaving a tail that decayed over many seconds after light termination. The antibodies also caused spectrally neutral flashes to elicit prolonged aftercurrents in the absence of large metarhodopsin accumulation; such aftercurrents could be quenched by chromatic illumination that photoconverts metarhodopsin back to rhodopsin. These observations indicate that the antibodies depleted functionally available arrestin, and implicate this molecule in the deactivation of the photoresponse at the rhodopsin level.

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“…High levels of calcium inhibited phosphorylation of nietarhodopsin and increase dephosphorylation of rhodopsin (Paulsen and Bentrop, 1984;Bentrop and Paulsen, 1986). However, this light induced reversible phosphorylation of opsin could not be observed in isolated octopus photoreceptor membranes (Paulsen and Hoppe, 1978). Electrophysiology of Limulus ventral photoreceptor showed that rhodopsin photoregenerated from inactive metarhodopsin generated no receptor potential after absorbing a photon.…”

Section: G-proteinmentioning

confidence: 91%

“…The function of opsin phosphorylation in vertebrates may be to terminate the ability of metarhodopsin to activate cGMP phosphodiesterase (Sitaramayya and Liebman, 1983). Phosphorylation of invertebrate opsin following the conversion of rhodopsin into metarhodopsin has been shown to occur in octopus (Paulsen and Hoppe, 1978) and flies (Matsumoto et al, 1982;Paulsen and Bentrop, 1984). If the phosphorylation of metarhodopsin is involved in the termination of physiologically active metarhodopsin state then photoconversion of metarhodopsin into rhodopsin would be expected to inhibit the phosphorylation of opsin and to initiate the dephosphorylation of phosphorylated opsin.…”

Section: G-proteinmentioning

confidence: 99%

Photoreception and Phototransduction in Invertebrate Photoreceptors

Tsuda

1987

Photochem & Photobiology

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Light‐activated phosphorylation of cephalopod rhodopsin

Cited by 34 publications

References 21 publications

Identification of a Single Phosphorylation Site Within Octopus Rhodopsin

Identification of a Single Phosphorylation Site Within Octopus Rhodopsin

Arrestin in Ciliary Invertebrate Photoreceptors: Molecular Identification and Functional AnalysisIn Vivo

Photoreception and Phototransduction in Invertebrate Photoreceptors

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