Chicken red‐sensitive cone visual pigment retains a binding domain for transducin

Fukada, Yoshitaka; Okano, Toshiyuki; Artamonov, I. D.; Yoshizawa, Tôru

doi:10.1016/0014-5793(89)80255-8

Cited by 21 publications

(18 citation statements)

References 12 publications

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“…cG and mG at 0 -37°C. It should be noted that this finding is inconsistent with previous reports showing that the initial velocity of G t activation by cone visual pigments was similar to that of rhodopsin (7,9,10). The previous studies were performed in the presence of about a 10-fold excess of G t using the pigments in liposomes or native membranes at 0 or 4°C.…”

Section: Discussioncontrasting

confidence: 93%

“…It has been reported previously that the G t activation efficiencies of rhodopsin and cone visual pigments were similar to each other based on experiments performed at about 0°C (7,9,10), although those of rhodopsin and cone visual pigments of a poikilothermic animal (carp) were recently reported to be different at 20°C (11,12). Thus, it is likely that the difference in amplification efficiency between wild-type rods and rods con-taining mG is caused by temperature-dependent intrinsic properties of visual pigments such as the thermal equilibrium between active state Meta-II and its precursor Meta-I and/or the lifetime of Meta-II that may compete with the deactivation process consisting of phosphorylation by rhodopsin kinase (7).…”

supporting

confidence: 74%

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Rod Visual Pigment Optimizes Active State to Achieve Efficient G Protein Activation as Compared with Cone Visual Pigments

Kojima

Imamoto

Maeda

et al. 2014

Journal of Biological Chemistry

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Section: Discussioncontrasting

confidence: 93%

supporting

confidence: 74%

Rod Visual Pigment Optimizes Active State to Achieve Efficient G Protein Activation as Compared with Cone Visual Pigments

Kojima

Imamoto

Maeda

et al. 2014

Journal of Biological Chemistry

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“…Nevertheless, rods and cones exhibit distinctive light responses: Rods have several hundred times higher sensitivity to light than cones, whereas cones recover from photoexcitation much faster than rods (Baylor 1996), and the molecular mechanism(s) underlying these differences largely remains to be elucidated. The activation kinetics of transducin by cone pigments was similar to that by rhodopsin (Fukada et al . 1989; Starace and Knox 1997), and the photoresponse recorded from the transgenic Xenopus rods expressing cone pigment was indistinguishable from that of the wild‐type rods (Kefalov et al .…”

mentioning

confidence: 73%

GRK1 and GRK7: Unique cellular distribution and widely different activities of opsin phosphorylation in the zebrafish rods and cones

Wada

Sugiyama

Okano

et al. 2006

Journal of Neurochemistry

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Retinal cone cells exhibit distinctive photoresponse with a more restrained sensitivity to light and a more rapid shutoff kinetics than those of rods. To understand the molecular basis for these characteristics of cone responses, we focused on the opsin deactivation process initiated by G protein-coupled receptor kinase (GRK) 1 and GRK7 in the zebrafish, an animal model suitable for studies on retinal physiology and biochemistry. Screening of the ocular cDNAs identified two homologs for each of GRK1 (1A and 1B) and GRK7 (7-1 and 7-2), and they were classified into three GRK subfamilies, 1 A, 1B and 7 by phylogenetic analysis. In situ hybridization and immunohistochemical studies localized both GRK1B and GRK7-1 in the cone outer segments and GRK1A in the rod outer segments. The opsin/GRKs molar ratio was estimated to be 569 in the rod and 153 in the cone. The recombinant GRKs phosphorylated light-activated rhodopsin, and the V max value of the major cone subtype, GRK7-1, was 32-fold higher than that of the rod kinase, GRK1A. The reinforced activity of the cone kinase should provide a strengthened shutoff mechanism of the light-signaling in the cone and contribute to the characteristics of the cone responses by reducing signal amplification efficiency.

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“…Previously, several studies on the chicken red cone pigment have demonstrated that it activates transducin (4,25,27) and the cGMP phosphodiesterase (28) and is a substrate for rhodopsin kinase (29). Although these studies have demonstrated the basic interactions, kinetic comparisons relevant to cone-rod physiological differences were not carried out.…”

Section: Discussionmentioning

confidence: 99%

Activation of Transducin by a Xenopus Short Wavelength Visual Pigment

Starace

Knox

1997

Journal of Biological Chemistry

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Phototransduction in cones differs significantly from that in rods in sensitivity, kinetics, and recovery following exposure to light. The contribution that the visual pigment makes in determining the cone response was investigated biochemically by expressing a Xenopus violet cone opsin (VCOP) cDNA in COS1 cells and assaying the light-dependent activation of transducin. Light-exposed VCOP stimulated [35 S]guanosine 5-(␥-thio)triphosphate nucleotide exchange on bovine rod transducin in a time-dependent manner with a half-time for activation of 0.75 min, similar to that of bovine rhodopsin. In exhaustive binding assays, VCOP and rhodopsin activity showed similar concentration dependence with half-maximal activation occurring at 0.02 mol of pigment/mol of transducin. Although VCOP was able to activate as many as 12 transducins per photoisomerization, rhodopsin catalyzed significantly more. When assays were performed with > 420 nm illumination, VCOP exhibited rapid regeneration and high affinity for the photoregenerated 11-cis-retinal. Recycling of the chromophore and reactivation of the pigment resulted in multiple activations of transducin, whereas a maximum of 1 transducin per VCOP was activated under brief illumination. The decay of the active species formed following photobleaching was complete in <5 min, ϳ10-fold faster than that of rhodopsin. In vitro, VCOP activated rod transducin with kinetics and affinity similar to those of rhodopsin, but the active conformation decayed more rapidly and the apoprotein regenerated more efficiently with VCOP than with rhodopsin. These properties of the violet pigment may account for much of the difference in response kinetics between rods and cones.Photopic vision is mediated by specialized photoreceptor cone cells that function at high levels of illumination, respond to rapid changes in light, and permit color discrimination (1, 2). Each cone cell expresses a cone opsin. The cone opsins are members of a larger family of visual pigments (3-5) and share significant amino acid sequence homology with the rod pigment rhodopsin (6). Among the cone pigments, the short wavelength pigments (Group S, with wavelengths of peak absorbance ( max ) 1 ϳ 415-440 nm) permit vision in the violet/blue region of the spectrum and are represented by the mammalian blue, chicken violet, and Xenopus violet pigments.2 Although cone cells expressing Group S pigments are in the minority in the vertebrate retina, they are an integral part of vision. For example, in blue monochromats, i.e. humans with red-green pigment mutations, the blue opsin is the sole mediator of photopic vision (7,8).The phototransduction mechanisms have been extensively investigated in rods (for reviews see Refs. 2 and 9). Following absorption of light and isomerization of 11-cis-retinal to alltrans-retinal, rhodopsin undergoes a series of conformational changes that eventually leads to a transient state, coincident with metarhodopsin(II) (MetaII), that activates the second messenger cascade (9). MetaII interacts with the heterot...

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Chicken red‐sensitive cone visual pigment retains a binding domain for transducin

Cited by 21 publications

References 12 publications

Rod Visual Pigment Optimizes Active State to Achieve Efficient G Protein Activation as Compared with Cone Visual Pigments

Rod Visual Pigment Optimizes Active State to Achieve Efficient G Protein Activation as Compared with Cone Visual Pigments

GRK1 and GRK7: Unique cellular distribution and widely different activities of opsin phosphorylation in the zebrafish rods and cones

Activation of Transducin by a Xenopus Short Wavelength Visual Pigment

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