Formation of a 7‐<i>cis</i> retinal pigment by irradiating cattle rhodopsin at low temperatures

Maeda, Akio; Ogurusu, Tarou; Shichida, Yoshinori; Tokunaga, Fumio; Yoshizawa, Tôru

doi:10.1016/0014-5793(78)80725-x

Cited by 36 publications

(23 citation statements)

References 13 publications

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“…Purification of 7- cis retinal from ipRGCs would provide a confirmation of this idea, though such experiments are challenging due to the miniscule amount of melanopsin in the retina (Berson et al, 2010; Do et al, 2009; Ecker et al, 2010). Such confirmation would motivate investigation of how melanopsin forms this isomer naturally while other pigments require artificial conditions (Azuma and Azuma, 1985; Maeda et al, 1978; Maeda et al, 1979); intriguingly, simulations already suggest that retinal has a distinct geometry when bound within melanopsin (Sekharan et al, 2012). …”

Section: Discussionmentioning

confidence: 99%

Melanopsin Tristability for Sustained and Broadband Phototransduction

Emanuel

2015

Neuron

115

134

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SUMMARY Mammals rely upon three ocular photoreceptors to sense light: rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs). Rods and cones resolve details in the visual scene. Conversely, ipRGCs integrate over time and space, primarily to support “non-image” vision. The integrative mechanisms of ipRGCs are enigmatic, particularly since these cells use a phototransduction motif that allows invertebrates like Drosophila to parse light with exceptional temporal resolution. Here, we provide evidence for a single mechanism that allows ipRGCs to integrate over both time and wavelength. Light distributes the visual pigment, melanopsin, across three states, two silent and one signaling. Photoequilibration among states maintains pigment availability for sustained signaling, stability of the signaling state permits minutes-long temporal summation, and modest spectral separation of the silent states promotes uniform activation across wavelengths. By broadening the tuning of ipRGCs in both temporal and chromatic domains, melanopsin tristability produces signal integration for physiology and behavior.

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Section: Discussionmentioning

confidence: 99%

Melanopsin Tristability for Sustained and Broadband Phototransduction

Emanuel

2015

Neuron

115

134

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“…Therefore, the fact that P-466 was not produced at liquid nitrogen temperature suggests that the formation of P-466 from P-495 is due not to the twisting around the c14<15 single bond but to that around the c8<9 single bond. In fact, irradiation of rhodopsin above -70 "C produced a photoproduct that has 7-cis-retinal as its chromophore (Maeda et al, 1978), suggesting that the chromophore-binding site above this temperature became flexible enough to accommodate the twisted chromophore around the c 8 4 9 single bond. Furthermore, the twist around the C8-C9 single bond may assist in increasing the coplanarity between the plane of the @-ionone ring and that of the C7-cS double bond, resulting in the decrease of the @-band of the CD spectrum in the course of the photoconversion of P-495 to P-466.…”

Section: Discussionmentioning

confidence: 99%

Studies on structure and function of rhodopsin by use of cyclopentatrienylidene 11-cis-locked-rhodopsin

Fukada¹,

Shichida²,

Yoshizawa³

et al. 1984

Biochemistry

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The photochemical reaction of cyclopentatrienylidene 11-cis-locked-rhodopsin derived from cyclopentatrienylidene 11-cis-locked-retinal and cattle opsin was spectrophotometrically studied. The difference absorption spectrum between the cyclopentatrienylidene 11-cis-locked-rhodopsin and its retinal oxime had its maximum at 495 nm (P-495). Irradiation of P-495 at -196 degrees C with either blue light or orange light caused no spectral change, supporting the cis-trans isomerization hypothesis for formation of bathorhodopsin. Upon irradiation of P-495 at 0 degree C with orange light, however, its absorption spectrum shifted to a shorter wavelength owing to formation of a hypsochromic product. The difference absorption spectrum between this product (P-466) and its retinal oxime showed its maximum at 466 nm. Analysis of retinal isomers by high-performance liquid chromatography showed that this spectral shift was not accompanied by photoisomerization of the chromophore. P-466 could almost completely be photoconverted to the original pigment (P-495) by irradiation at 0 degree C with blue light with little formation of the other isomeric form of its chromophore. The alpha-band of the circular dichroism spectrum of P-495 was very small in comparison with that of rhodopsin, while that of P-466 was comparable to it. These facts suggest that P-495 has a planar conformation in the side chain of the chromophore and that P-466 has a twisted one, probably at the C8-C9 single bond. Cyclic-GMP phosphodiesterase in frog rod outer segment was activated by neither P-495 nor P-466. This result suggests that the isomerization of the retinylidene chromophore of rhodopsin is indispensable in the phototransduction process.

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“…It should be pointed out that in experiments in which the period of 480-nm illumination of the mixture was greatly increased, the concentration of rhodopsin plus isorhodopsin eventually decreased as expected (a photostationary state at 770K with 476-nm light contains only -37% rhodopsin plus isorhodopsin [Oseroff and Callender, 1974]). With respect to the identity of the L' isomer, Maeda et al (1978) found that quasi-photostationary states of rhodopsin at -750C (a temperature at which lumirhodopsin is found) contain small amounts of 7-cis and 13-cis retinal. However, these experiments were performed under conditions (degree of illumination, temperature) considerably different than in the present study.…”

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confidence: 99%

The photoconversion of lumirhodopsin at 77 degrees K. Estimation of the quantum efficiency

Becher¹

1980

Biophysical Journal

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Evidence is presented that lumirhodopsin (containing all-trans retinal) is not directly photoconverted to bathorhodopsin (all-trans) at 77 degrees K as previously suggested (Yoshizawa and Wald. 1963. Nature (Lond.) 197:1279-1286). Rather, lumirhodopsin is converted to a new species, L' (11-cis and/or 9-cis retinal) which, on warming to room temperature, is indistinguishable from rhodopsin or isorhodopsin. The quantum efficiency for the conversion of lumirhodopsin to L' is estimated to be 0.5 +/- 0.1. This value is significantly higher than that of other all-trans to cis conversions for bovine rhodopsin intermediates, indicating that the opsin conformation has a significant effect on a pigment's quantum efficiency.

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Formation of a 7‐cis retinal pigment by irradiating cattle rhodopsin at low temperatures

Cited by 36 publications

References 13 publications

Melanopsin Tristability for Sustained and Broadband Phototransduction

Melanopsin Tristability for Sustained and Broadband Phototransduction

Studies on structure and function of rhodopsin by use of cyclopentatrienylidene 11-cis-locked-rhodopsin

The photoconversion of lumirhodopsin at 77 degrees K. Estimation of the quantum efficiency

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