Light-dependent Activation of Rod Transducin by Pineal Opsin

Max, Marianna; Surya, Arjun; Takahashi, Joseph S.; Margolskee, Robert F.; Knox, Barry E.

doi:10.1074/jbc.273.41.26820

Cited by 28 publications

(19 citation statements)

References 69 publications

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“…A number of unique genes that are expressed in these cells do not appear to be expressed in other tissue. In addition to SPACRCAN (Wang et al, 1996;Acharya et al, 2000), retinal photoreceptors and pinealocytes also synthesize interstitial retinol-binding protein (IRBP; Rodrigues et al, 1986), cone arrestin (Craft et al, 1994), opsins (Vigh et al, 1998), transducin (Max et al, 1998), and several other proteins involved in the phototransduction cascade (Blackshaw and Snyder, 1997).…”

Section: Discussionmentioning

confidence: 97%

SPACRCAN in the developing retina and pineal gland of the rat: Spatial and temporal pattern of gene expression and protein synthesis

Foletta

Nishiyama

Rayborn

et al. 2001

J of Comparative Neurology

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SPACRCAN is a hyaluronan-binding proteoglycan that is present in the pineal gland and interphotoreceptor matrix of the retina. Here, we evaluate the pattern of SPACRCAN gene expression and protein appearance during retinal and pineal gland development in the rat. In situ hybridization histochemistry with SPACRCAN riboprobes indicates that hybridization signals are first evident in the retina over developing photoreceptor cells at embryonic day 16 (E16) and in the pineal gland at E21. Immunocytochemistry using a SPACRCAN antibody shows localization of SPACRCAN protein in the developing interphotoreceptor matrix by Postnatal day 5 (P5) and in the pineal gland by P6. These studies suggest that SPACRCAN mRNA expression may occur substantially earlier than the time when SPACRCAN protein is detectable in both the retina and the pineal gland. The period of retinal histogenesis when SPACRCAN is detected first is coincident with the time photoreceptors begin to extend from the outer retinal surface, suggesting that SPACRCAN may participate in the maturation and maintenance of the light-sensitive photoreceptor outer segment.

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Section: Discussionmentioning

confidence: 97%

SPACRCAN in the developing retina and pineal gland of the rat: Spatial and temporal pattern of gene expression and protein synthesis

Foletta

Nishiyama

Rayborn

et al. 2001

J of Comparative Neurology

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“…This opsin possesses the characteristic features of a visual opsin (equivalents of Lys-296, Glu-113, Cys-110 and Cys-187, and Asn-15), but its expression is restricted to the pineal and thus was named pinopsin. In vitro expression of chicken pinopsin and its reconstitution with 11-cis-retinal reveals that this opsin possesses a maximal absorbance (λ max ) of 470 nm (Nakamura et al 1999;Okano et al 1994) and 462 nm (Max et al 1998). Max et al (1995) confirmed the localisation of chicken pinopsin to the pineal and determined the structure of the gene.…”

Section: P-opsinmentioning

confidence: 98%

Opsins and mammalian photoentrainment

Bellingham

Foster

2002

Cell Tissue Res

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Research over the past decade has provided overwhelming evidence that photoreception in the vertebrate eye is not confined to the rod and cone photoreceptors. It appears that photoreceptor cells within the inner retina provide irradiance information to a wide variety of different photosensory tasks including photoentrainment, pupillary constriction and masking behaviour. Action spectra in mice lacking all rod and cone photoreceptors ( rd/rd cl) have demonstrated the existence of a previously uncharacterised, opsin/vitamin-A-based photopigment with peak sensitivity at 479 nm (opsin photopigment/OP(479)). The review addresses the question: has the gene encoding OP(479) already been isolated, and if not, what type of gene should we be seeking and where in the eye might this gene be expressed? On the basis of available data, the gene that encodes OP(479) remains unidentified, and two broad possibilities exist. On the assumption that OP(479) will be like all of the other vertebrate photopigments (ocular and extraocular) and share a close phylogenetic relationship based upon amino acid identity and a conserved genomic structure, then the gene encoding OP(479) has yet to be isolated. Alternatively, there may have been a separate line of photopigment evolution in the vertebrates that has given rise to the melanopsin family. If true then the mammalian melanopsin gene may encode OP(479). Only when melanopsin and other candidates for OP(479) have been functionally expressed, and shown to encode a photopigment that matches the action spectrum of OP(479), can firm conclusions about the identity of the non-rod, non-cone ocular photoreceptor of mammals be made.

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“…Light-dependent activation of bovine transducin by using filter binding assays were carried out as described (16,18).…”

Section: Methodsmentioning

confidence: 99%

Vertebrate ultraviolet visual pigments: Protonation of the retinylidene Schiff base and a counterion switch during photoactivation

Kusnetzow

Dukkipati

Babu

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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For visual pigments, a covalent bond between the ligand (11-cisretinal) and receptor (opsin) is crucial to spectral tuning and photoactivation. All photoreceptors have retinal bound via a Schiff base (SB) linkage, but only UV-sensitive cone pigments have this moiety unprotonated in the dark. We investigated the dynamics of mouse UV (MUV) photoactivation, focusing on SB protonation and the functional role of a highly conserved acidic residue (E108) in the third transmembrane helix. On illumination, wild-type MUV undergoes a series of conformational changes, batho 3 lumi 3 meta I, finally forming the active intermediate meta II. During the dark reactions, the SB becomes protonated transiently. In contrast, the MUV-E108Q mutant formed significantly less batho that did not decay through a protonated lumi. Rather, a transition to meta I occurred above Ϸ240 K, with a remarkable red shift ( max Ϸ 520 nm) accompanying SB protonation. The MUV-E108Q meta I 3 meta II transition appeared normal but the MUV-E108Q meta II decay to opsin and free retinal was dramatically delayed, resulting in increased transducin activation. These results suggest that there are two proton donors during the activation of UV pigments, the primary counterion E108 necessary for protonation of the SB during lumi formation and a second one necessary for protonation of meta I. Inactivation of meta II in SWS1 cone pigments is regulated by the primary counterion. Computational studies suggest that UV pigments adopt a switch to a more distant counterion, E176, during the lumi to meta I transition. The findings with MUV are in close analogy to rhodopsin and provides further support for the importance of the counterion switch in the photoactivation of both rod and cone visual pigments.V isual pigments are seven transmembrane ␣-helical proteins that initiate the light transduction pathway in retinal photoreceptors. Whereas other G protein-coupled receptors interact with their ligands noncovalently, the visual pigments consist of 11-cis-retinal covalently attached to the apoprotein via a Schiff base (SB) linkage to a conserved lysine in transmembrane helix 7 (TM7) (Fig. 1). After absorption of light, the retinal chromophore isomerizes to the all-trans conformation and triggers a series of conformational changes that lead to the formation of the active state, R* or meta II. All-trans-retinal is eventually released from the vertebrate apoprotein, and the visual pigment can be regenerated with 11-cis-retinal.In dark-adapted rhodopsin, the SB pK a is extraordinarily high resulting in a protonated SB buried within the chromophore binding site (1). The protonation is important to prevent the spontaneous hydrolysis of the SB and contributes to the max (2, 3). The binding site of rhodopsin is neutral (4), and E113 serves as a counterion to the protonated SB (5-8). The stability of the salt bridge is enhanced by a single water molecule that interacts with the side chains of E113 and indirectly through a second water molecule that interacts with adjacent residues (9,...

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Light-dependent Activation of Rod Transducin by Pineal Opsin

Cited by 28 publications

References 69 publications

SPACRCAN in the developing retina and pineal gland of the rat: Spatial and temporal pattern of gene expression and protein synthesis

SPACRCAN in the developing retina and pineal gland of the rat: Spatial and temporal pattern of gene expression and protein synthesis

Opsins and mammalian photoentrainment

Vertebrate ultraviolet visual pigments: Protonation of the retinylidene Schiff base and a counterion switch during photoactivation

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