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de Grip WJ, Ganapathy S. Rhodopsins: An Excitingly Versatile Protein Species for Research, Development and Creative Engineering. Front Chem 2022; 10:879609. [PMID: 35815212 PMCID: PMC9257189 DOI: 10.3389/fchem.2022.879609] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 05/16/2022] [Indexed: 01/17/2023] Open
Abstract
The first member and eponym of the rhodopsin family was identified in the 1930s as the visual pigment of the rod photoreceptor cell in the animal retina. It was found to be a membrane protein, owing its photosensitivity to the presence of a covalently bound chromophoric group. This group, derived from vitamin A, was appropriately dubbed retinal. In the 1970s a microbial counterpart of this species was discovered in an archaeon, being a membrane protein also harbouring retinal as a chromophore, and named bacteriorhodopsin. Since their discovery a photogenic panorama unfolded, where up to date new members and subspecies with a variety of light-driven functionality have been added to this family. The animal branch, meanwhile categorized as type-2 rhodopsins, turned out to form a large subclass in the superfamily of G protein-coupled receptors and are essential to multiple elements of light-dependent animal sensory physiology. The microbial branch, the type-1 rhodopsins, largely function as light-driven ion pumps or channels, but also contain sensory-active and enzyme-sustaining subspecies. In this review we will follow the development of this exciting membrane protein panorama in a representative number of highlights and will present a prospect of their extraordinary future potential.
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Affiliation(s)
- Willem J. de Grip
- Leiden Institute of Chemistry, Department of Biophysical Organic Chemistry, Leiden University, Leiden, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Srividya Ganapathy
- Department of Imaging Physics, Delft University of Technology, Netherlands
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Trifonov L, Rothstein A, Korshin EE, Viskind O, Afri M, Leitus G, Palczewski K, Gruzman A. Straightforward Access to Terminally Disubstituted Electron‐Deficient Alkylidene Cyclopent‐2‐en‐4‐ones through Olefination with α‐Carbonyl and α‐Cyano Secondary Alkyl Sulfones. European J Org Chem 2021. [DOI: 10.1002/ejoc.202101258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Lena Trifonov
- Department of Chemistry, Bar-Ilan University Max and Anna Webb St. Ramat-Gan 5290002 Israel
| | - Ayelet Rothstein
- Department of Chemistry, Bar-Ilan University Max and Anna Webb St. Ramat-Gan 5290002 Israel
| | - Edward E. Korshin
- Department of Chemistry, Bar-Ilan University Max and Anna Webb St. Ramat-Gan 5290002 Israel
| | - Olga Viskind
- Department of Chemistry, Bar-Ilan University Max and Anna Webb St. Ramat-Gan 5290002 Israel
| | - Michal Afri
- Department of Chemistry, Bar-Ilan University Max and Anna Webb St. Ramat-Gan 5290002 Israel
| | - Gregory Leitus
- Department of Chemical Research Support the Weizmann Institute of Science Rehovot 76100 Israel
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute Department of Ophthalmology and Departments of Physiology and Biophysics and Chemistry and Molecular Biology and Biochemistry, University of California Irvine CA 92697 USA
| | - Arie Gruzman
- Department of Chemistry, Bar-Ilan University Max and Anna Webb St. Ramat-Gan 5290002 Israel
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Abstract
"Retinoid" is the general term for vitamin A derivatives and chemical compounds that act like vitamin A. Vitamin A are composed of four isoprene units and are named according to their terminal functional group, such as retinol (OH, 1), retinal (CHO, 2), and retinoic acid (CO2H, 3). Vitamin A usually refers to retinol. In the past few decades, major advances in research on vitamin A have improved our understanding of its fundamental roles and physiological significance in living cells. In this review, three types of chemical biology studies using vitamin A analogs are described: (1) conformational studies of the chromophore in retinal proteins (rhodopsin, phoborhodopsin, and retinochrome), especially the conformation around the cyclohexene ring; (2) structure-activity relationship studies of retinoic acid analogs to create new signaling molecules for activating nuclear receptors; and (3) development of a new channelrhodopsin with an absorption maximum at longer wavelength to overcome the various demerits of channelrhodopsins used in optogenetics, as well as the stereoselective synthesis of retinoid isomers and their analogs using a diene-tricarbonyliron complex or a palladium-catalyzed cross-coupling reaction between vinyl triflates and stannyl olefins.
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Schapiro I. The Origin of Bond Selectivity and Excited-State Reactivity in Retinal Analogues. J Phys Chem A 2016; 120:3353-65. [DOI: 10.1021/acs.jpca.6b00701] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Igor Schapiro
- Fritz Haber
Center for Molecular
Dynamics, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Nakanishi K, Crouch R. Application of Artificial Pigments to Structure Determination and Study of Photoinduced Transformations of Retinal Proteins. Isr J Chem 2013. [DOI: 10.1002/ijch.199500030] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Yabushita A, Kobayashi T, Tsuda M. Time-Resolved Spectroscopy of Ultrafast Photoisomerization of Octopus Rhodopsin under Photoexcitation. J Phys Chem B 2012; 116:1920-6. [DOI: 10.1021/jp209356s] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Atsushi Yabushita
- Department
of Electrophysics, National Chiao-Tung University, Hsinchu 300, Taiwan
| | - Takayoshi Kobayashi
- Department
of Electrophysics, National Chiao-Tung University, Hsinchu 300, Taiwan
- CREST, Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi, Saitama
332-0012, Japan
- Department
of Applied Physics
and Chemistry and Institute for Laser Science, University of Electro-Communications, 1-5-1, Chofugaoka, Chofu,
Tokyo 182-8585, Japan
- Institute
of Laser Engineering, Osaka University,
2-6 Yamada-oka, Suita, Osaka 565-0971,
Japan
| | - Motoyuki Tsuda
- Kagawa School of
Pharmaceutical
Sciences, Tokushima Bunri University, 1314-1
Shido, Sanuki, Kagawa 769-2193, Japan
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7
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Is the lifetime of light-stimulated cGMP phosphodiesterase regulated by recoverin through its regulation of rhodopsin phosphorylation? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00039522] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Pescitelli G, Sreerama N, Salvadori P, Nakanishi K, Berova N, Woody RW. Inherent Chirality Dominates the Visible/Near-Ultraviolet CD Spectrum of Rhodopsin. J Am Chem Soc 2008; 130:6170-81. [DOI: 10.1021/ja711009y] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Gennaro Pescitelli
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Pisa, via Risorgimento 35, I-56126 Pisa, Italy, Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, and Department of Chemistry, Columbia University, 3000 Broadway, MC 3114, New York 10027
| | - Narasimha Sreerama
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Pisa, via Risorgimento 35, I-56126 Pisa, Italy, Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, and Department of Chemistry, Columbia University, 3000 Broadway, MC 3114, New York 10027
| | - Piero Salvadori
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Pisa, via Risorgimento 35, I-56126 Pisa, Italy, Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, and Department of Chemistry, Columbia University, 3000 Broadway, MC 3114, New York 10027
| | - Koji Nakanishi
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Pisa, via Risorgimento 35, I-56126 Pisa, Italy, Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, and Department of Chemistry, Columbia University, 3000 Broadway, MC 3114, New York 10027
| | - Nina Berova
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Pisa, via Risorgimento 35, I-56126 Pisa, Italy, Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, and Department of Chemistry, Columbia University, 3000 Broadway, MC 3114, New York 10027
| | - Robert W. Woody
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Pisa, via Risorgimento 35, I-56126 Pisa, Italy, Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, and Department of Chemistry, Columbia University, 3000 Broadway, MC 3114, New York 10027
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Send R, Sundholm D. The Role of the β-Ionone Ring in the Photochemical Reaction of Rhodopsin. J Phys Chem A 2006; 111:27-33. [PMID: 17201384 DOI: 10.1021/jp065510f] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Time-dependent density functional theory (TDDFT) calculations on the photoabsorption process of the 11-cis retinal protonated Schiff base (PSB) chromophore show that the Franck-Condon relaxation of the first excited state of the chromophore involves a torsional twist motion of the beta-ionone ring relative to the conjugated retinyl chain. For the ground state, the beta-ionone ring and the retinyl chain of the free retinal PSB chromophore form a -40 degrees dihedral angle as compared to -94 degrees for the first excited state. The double bonds of the retinal are shorter for the fully optimized structure of the excited state than for the ground state suggesting a higher cis-trans isomerization barrier for the excited state than for the ground state. According to the present TDDFT calculations, the excitation of the retinal PSB chromophore does not primarily lead to a reaction along the cis-trans torsional coordinate at the C11-C12 bond. The activation of the isomerization center seems to occur at a later stage of the photo reaction. The results obtained at the TDDFT level are supported by second-order Møller-Plesset (MP2) and approximate singles and doubles-coupled cluster (CC2) calculations on retinal chromophore models; the MP2 and CC2 calculations yield for them qualitatively the same ground state and excited-state structures as obtained in the density functional theory and TDDFT calculations.
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Affiliation(s)
- Robert Send
- Institut für Physikalische Chemie, Universität Karlsruhe, Kaiserstrasse 12, D-76128 Karlsruhe, Germany
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Ikegami S, Iimori T, Sudo M, Kitsukawa M, Foroumadi A, Yonemura T, Takahashi H, Kizaki K, Ishii H. Thrombomodulin induction in cultured human endothelial cells by 9-cis-locked retinoic acid analogues. Bioorg Med Chem 2006; 14:5099-109. [PMID: 16713268 DOI: 10.1016/j.bmc.2006.04.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Revised: 04/03/2006] [Accepted: 04/04/2006] [Indexed: 11/16/2022]
Abstract
9-cis-Retinoic acid (RA) analogues devised to lock the 9-cis double bond by ring formation were synthesized using two stereoselective carbon-carbon bond formation reactions as key steps. The palladium-mediated Suzuki reaction was adopted to construct a 7E-double bond (RA numbering) and the Horner-Emmons olefination was employed for stereoselective 11E-double bond (RA numbering) formation. The synthesized 9-cis-RA analogues that are locked by five-membered ring systems (cyclopentene, dihydrofuran, and dihydrothiophene) were shown to have comparable thrombomodulin induction activities to that of 9-cis RA. Conformational analysis of these compounds showed their similarity to 9-cis RA in the spatial orientation of the side chain and the terminal carboxy group.
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Affiliation(s)
- Shiro Ikegami
- Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa 199-0195, Japan.
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Gascon JA, Batista VS. QM/MM study of energy storage and molecular rearrangements due to the primary event in vision. Biophys J 2004; 87:2931-41. [PMID: 15339806 PMCID: PMC1304767 DOI: 10.1529/biophysj.104.048264] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The energy storage and the molecular rearrangements due to the primary photochemical event in rhodopsin are investigated by using quantum mechanics/molecular mechanics hybrid methods in conjunction with high-resolution structural data of bovine visual rhodopsin. The analysis of the reactant and product molecular structures reveals the energy storage mechanism as determined by the detailed molecular rearrangements of the retinyl chromophore, including rotation of the (C11-C12) dihedral angle from -11 degrees in the 11-cis isomer to -161 degrees in the all-trans product, where the preferential sense of rotation is determined by the steric interactions between Ala-117 and the polyene chain at the C13 position, torsion of the polyene chain due to steric constraints in the binding pocket, and stretching of the salt bridge between the protonated Schiff base and the Glu-113 counterion by reorientation of the polarized bonds that localize the net positive charge at the Schiff-base linkage. The energy storage, computed at the ONIOM electronic-embedding approach (B3LYP/6-31G*:AMBER) level of theory and the S0-->S1 electronic-excitation energies for the dark and product states, obtained at the ONIOM electronic-embedding approach (TD-B3LYP/6-31G*//B3LYP/6-31G*:AMBER) level of theory, are in very good agreement with experimental data. These results are particularly relevant to the development of a first-principles understanding of the structure-function relations in prototypical G-protein-coupled receptors.
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Affiliation(s)
- Jose A Gascon
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA
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18
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Fan G, Siebert F, Sheves M, Vogel R. Rhodopsin with 11-cis-locked chromophore is capable of forming an active state photoproduct. J Biol Chem 2002; 277:40229-34. [PMID: 12177057 DOI: 10.1074/jbc.m205033200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The visual pigment rhodopsin is characterized by an 11-cis retinal chromophore bound to Lys-296 via a protonated Schiff base. Following light absorption the C(11)=C(12) double bond isomerizes to trans configuration and triggers protein conformational alterations. These alterations lead to the formation of an active intermediate (Meta II), which binds and activates the visual G protein, transducin. We have examined by UV-visible and Fourier transform IR spectroscopy the photochemistry of a rhodopsin analogue with an 11-cis-locked chromophore, where cis to trans isomerization around the C(11)=C(12) double bond is prevented by a 6-member ring structure (Rh(6.10)). Despite this lock, the pigment was found capable of forming an active photoproduct with a characteristic protein conformation similar to that of native Meta II. This intermediate is further characterized by a protonated Schiff base and protonated Glu-113, as well as by its ability to bind a transducin-derived peptide previously shown to interact efficiently with native Meta II. The yield of this active photointermediate is pH-dependent and decreases with increasing pH. This study shows that with the C(11)=C(12) double bond being locked, isomerization around the C(9)=C(10) or the C(13)=C(14) double bonds may well lead to an activation of the receptor. Additionally, prolonged illumination at pH 7.5 produces a new photoproduct absorbing at 385 nm, which, however, does not exhibit the characteristic active protein conformation.
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Affiliation(s)
- Guibao Fan
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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19
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Metzler DE, Metzler CM, Sauke DJ. Light and Life. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50026-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Lou J, Tan Q, Karnaukhova E, Berova N, Nakanishi K, Crouch RK. Synthetic retinals: convenient probes of rhodopsin and visual transduction process. Methods Enzymol 2000; 315:219-37. [PMID: 10736705 DOI: 10.1016/s0076-6879(00)15846-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Affiliation(s)
- J Lou
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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Lou J, Hashimoto M, Berova N, Nakanishi K. Enantioselective binding of an 11-cis-locked cyclopropyl retinal. The conformation of retinal in bovine rhodopsin. Org Lett 1999; 1:51-4. [PMID: 10822532 DOI: 10.1021/ol990048l] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[formula: see text] The conformation of the retinal chromophore in rhodopsin is central for understanding the visual transduction process. The absolute twist around the 12-s bond of the chromophore in rhodopsin has been determined by studies with 11-cis-locked 11,12-cyclopropylretinal analogues (11S,12R)-2 and (11R,12S)-3, enantioselectively synthesized with the aid of an enzyme. The finding that enantiomer 2 binds to opsin while the other 3 does not defines the absolute sense of twist around the 12-s bond.
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Affiliation(s)
- J Lou
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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23
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Colmenares LU, Niemczura WP, Asato AE, Liu RSH. A 19F NMR Study of Rhodopsin Analogs: Use of Vinylfluororetinal Chromophores. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp952850k] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Leticia U. Colmenares
- Department of Chemistry, 2545 The Mall, University of Hawaii, Honolulu, Hawaii 96822
| | - Walter P. Niemczura
- Department of Chemistry, 2545 The Mall, University of Hawaii, Honolulu, Hawaii 96822
| | - Alfred E. Asato
- Department of Chemistry, 2545 The Mall, University of Hawaii, Honolulu, Hawaii 96822
| | - Robert S. H. Liu
- Department of Chemistry, 2545 The Mall, University of Hawaii, Honolulu, Hawaii 96822
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Abstract
AbstractRecoverin is a Ca2+-binding protein found primarily in vertebrate photoreceptors. The proposed physiological function of recoverin is based on the finding that recoverin inhibits light-stimulated phosphorylation of rhodopsin. Recoverin interacts with rod outer segment membranes in a Ca2+-dependent manner. This interaction requires N-terminal acylation of recoverin. Four types of fatty acids have been detected on the N-terminus of recoverin, but the functional significance of this heterogeneous acylation is not yet clear.
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Future directions for rhodopsin structure and function studies. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractNMR (nuclear magnetic resonance) may be useful for determining the structure of retinal and its environment in rhodopsin, but not for determining the complete protein structure. Aggregation and low yield of fragments of rhodopsin may make them difficult to study by NMR. A long-term multidisciplinary attack on rhodopsin structure is required.
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More answers about cGMP-gated channels pose more questions. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractOur understanding of the molecular properties and cellular role of cGMP-gated channels in outer segments of vertebrate photo-receptors has come from over a decade of studies which have continuously altered and refined ideas about these channels. Further examination of this current view may lead to future surprises and further refine the understanding of cGMP-gated channels.
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Cyclic nucleotides as regulators of light-adaptation in photoreceptors. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractCyclic nucleotides can regulate the sensitivity of retinal rods to light through phosducin. The phosphorylation state of phosducin determines the amount of G available for activation by Rho*. Phosducin phosphorylation is regulated by cyclic nucleotides through their activation of cAMP-dependent protein kinase. The regulation of phosphodiesterase activity by the noncatalytic cGMP binding sites as well as Ca2+/calmodulin dependent regulation of cGMP binding to the cation channel are also discussed.
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Long term potentiation and CaM-sensitive adenylyl cyclase: Long-term prospects. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractThe type I CaM-sensitive adenylyl cyclase is in a position to integrate signals from multiple inputs, consistent with the requirements for mediating long term potentiation (LTP). Biochemical and genetic evidence supports the idea that this enzyme plays an important role inc LTP. However, more work is needed before we will be certain of the role that CaM-sensitive adenylyl cyclases play in LTP.
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Modulation of the cGMP-gated channel by calcium. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractCalcium acting through calmodulin has been shown to regulate the affinity of cyclic nucleotide-gated channels expressed in cell lines. But is calmodulin the Ca-sensor that normally regulates these channels?
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30
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How many light adaptation mechanisms are there? Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractThe generally positive response to our target article indicates that most of the commentators accept our contention that light adaptation consists of multiple and possibly redundant mechanisms. The commentaries fall into three general categories. The first deals with putative mechanisms that we chose not to emphasize. The second is a more extended discussion of the role of calcium in adaptation. Finally, additional aspects of cGMP involvement in adaptation are considered. We discuss each of these points in turn.
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Gene therapy, regulatory mechanisms, and protein function in vision. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractHereditary retinal degeneration due to mutations in visual genes may be amenable to therapeutic interventions that modulate, either positively or negatively, the amount of protein product. Some of the proteins involved in phototransduction are rapidly moved by a lightdependent mechanism between the inner segment and the outer segment in rod photoreceptor cells, and this phenomenon is important in phototransduction.
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A novel protein family of neuronal modulators. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractA number of proteins homologous to recoverin have been identified in the brains of the several vertebrate species. The brainderived members originally contain four EF-hand domains, but NH2- terminal domain is aberrant. Many of these proteins inhibited light-induced rhodopsin phosphorylation at high [Ca2+], suggesting that the brain-derived members may act as a Ca2+-sensitive modulator of receptor phosphorylation, as recoverin does.
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The structure of rhodopsin and mechanisms of visual adaptation. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractRapidly advancing studies on rhodopsin have focused on new strategies for crystallization of this integral membrane protein for x-ray analysis and on alternative methods for structural determination from nuclear magnetic resonance data. Functional studies of the interactions between the apoprotein and its chromophore have clarified the role of the chromophore in deactivation of opsin and in photoactivation of the pigment.
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Crucial steps in photoreceptor adaptation: Regulation of phosphodiesterase and guanylate cyclase activities and Ca 2+-buffering. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractThis commentary discusses the balance of phosphodiesterase and guanylate cyclase activities in vertebrate photoreceptors at moderate light intensities. The rate of cGMP hydrolysis and synthesis seem to equal each other. Ca2+ as regulator of both enzyme activities is also effectively buffered in photoreceptor cells by cytoplasmic buffer components.
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The atomic structure of visual rhodopsin: How and when? Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractStrong arguments are presented by Hargrave suggesting that the crystallization of visual rhodopsin for high resolution analysis by X-ray crystallography or electron microscopy is feasible. However, the effort needed to achieve this goal will most likely exceed the resources of a single laboratory and a concerted approach to the research is necessary.
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36
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Molecular insights gained from covalently tethering cGMP to the ligand-binding sites of retinal rod cGMP-gated channels. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractA photoaffinity analog of cGMP has been used to biochemically identify a new ligand-binding subunit of the retinal rod cGMP-activated ion channel, as well as amino acids in contact with cGMP in the original subunit. Covalent tethering of this probe to channels in excised menbrane patches has revealed a functional heteogeneity in the ligand-binding sites that may arise from the two biochemically identified subunits.
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37
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Abstract
AbstractRecent findings emphasize the complexity, both genetic and functional, of the manifold genes and mutations causing inherited retinal degeneration in humans. Knowledge of the genetic bases of these diseases can contribute to design of rational therapy, as well as elucidating the function of each gene product in normal visual processes.
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38
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Channel structure and divalent cation regulation of phototransduction. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractThe identification of additional subunits of the cGMP-gated cation channel suggests exciting questions about their regulatory roles and about structure/functional relationships. How do the different subunits interact? How is the complex assembled into the plasma membrane? Divalent cations have been implicated in the regulation of adaptation. One often overlooked cation is magnesium. Could this ion play a role in phototransduction?
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39
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Structure of the cGMP-gated channel. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x0003939x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractThe subunit structure of the cGMP-gated cation channel of rod photoreceptors is rapidly being defined, and in the process the mode of regulation by Ca2+-calmodulin unraveled. Intriguingly, early results suggest that additional subunits of unknown function are associated with the channel and remain to be identified.
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40
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Linking genotypes with phenotypes in human retinal degenerations: Implications for future research and treatment. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractAlthough undoubtedly it will be incomplete by the time it is published, the target article by Daiger et al. organizes mutations in genes that produce retinal degenerations in humans into categories of clinically relevant phenotypes. Such classifications should help us understand the link between altered photoreceptor cell proteins and subsequent cell death, and they may yield insight into methods for preventing consequent blindness.
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41
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Genetic and clinical heterogeneity in tapetal retinal dystrophies. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x0003925x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractLarge scale DNA-mutation screening in patients with hereditary retinal diseases greatly enhances our knowledge about retinal function and diseases. Scientists, clinicians, patients, and families involved with retinal disorders may directly benefit from these developments. However, certain aspects of this expanding knowledge, such as the correlation between genotype and phenotype, may be much more complicated than we expect at present.
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42
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The determination of rhodopsin structure may require alternative approaches. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractThe structure of rhodopsin is a subject of intense interest. Solving the structure by traditional methods has proved exceedingly challenging. It may therefore be useful to confront the problem by a combination of alternate techniques. These include FTIR (Fourier transform infrared spectroscopy) and AFM (atomic force microscopy) on the intact protein. Furthermore, additional insights may be gained through structural investigations of discrete rhodopsin domains.
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43
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Na-Ca + K exchanger and Ca 2+ homeostasis in retinal rod outer segments: Inactivation of the Ca 2+ efflux mode and possible involvement of intracellular Ca 2+ stores in Ca 2+ homeostasis. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractInactivation of the Ca2+ extrusion mode of the retinal rod Na- Ca + K exchanger is suggested to be the mechanism that prevents lowering of cytosolic free Ca2+ to < 1 nM when rod cells are saturated for a prolonged time under bright light conditions. Under these conditions, Ca2+ fluxes across disk membranes can contribute significantly to Ca2+ homeostasis in rods.
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44
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Nuclear magnetic resonance studies on the structure and function of rhodopsin. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractMagic angle spinning (MAS) NMR methods provide a means of obtaining high resolution structural data on rhodopsin and its photoin termediates. Current work has focused on the structure of the retinal chromophore and its interactions with surrounding protein charges. The recent development of MAS NMR methods for measuring internuclear distances with a resolution of ∼0.2 will complement diffraction methods for addressing key mechanistic questions.
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45
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Glutamate accumulation in the photoreceptor-presumed final common path of photoreceptor cell death. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractGenetic abnormalities of three factors related to the photoreceptor mechanism have been reported in both animal models and humans. Apoptotic mechanism has also been suggested as a final common pathway of photoreceptor cell death. Our findings of increased level of glutamate in photoreceptor cells in rds mice suggest that amino acid might mediate between these two pathological mechanisms.
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46
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Unique lipids and unique properties of retinal proteins. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractAmino-terminal heteroacylation has been identified in retinal proteins including recoverin and α subunit of G-protein, transducin. The tissue-specific modification seems to mediate not only a proteinmembrane interaction but also a specific protein-protein interaction. The mechanism generating the heterogeneity and its physiological role are still unclear, but an interesting idea for the latter postulates a fine regulation of the signal transduction pathway by distinct N-acyl groups.
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47
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Further insight into the structural and regulatory properties of the cGMP-gated channel. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractRecent studies from several different laboratories have provided further insight into structure-function relationships of cyclic nucleotide-gated channel and in particular the cCMPgated channel of rod photoreceptors. Site-directed mutagenesis and rod-olfactory chimeria constructs have defined important amino acids and peptide segments of the channel that are important in ion blockage, ligand specificity, and gating properties. Molecular cloning studies have indicated that cyclic nucleotide-gated channels consist of two subunits that are required to reproduce the properties of the native channels. Biochemical analysis of the cGMP-gated channel of rodcells have indicated that the 240 kDa protein that co-purifies with the 63 kDa channel subunit contains both the previously cloned second subunit of the channel and a glutamic acid-rich protein. The regulatory properties of the cGMP-gated channel from rod cells has also been studied in more detail. Studies indicate that the beta subunit of the cGMP-gated channel of rod cells contains the binding site for calmodulin. Interaction of calmodulin with the channel alters the apparent affinity of the channel for cGMP in all in vitro systems that have been studied. The significance of these recent studies are discussed in relation to the commentaries on the target article.
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48
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Unsolved issues in S-modulin/recoverin study. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractS-Modulin is a frog homolog of recoverin. The function and the underlying mechanism of the action of these proteins are now understood in general. However, there remain some unsolved issues including; two distinct effects of S-modulin; Ca2+-dependent binding of S-modulin to membranes and a possible target protein; S-modulin-like proteins in other neurons. These issues are considered in this commentary.
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49
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Mechanisms of photoreceptor degenerations. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractThe candidate gene approach has identified many causes of photoreceptor rod cell death in retinitis pigmentosa. Some mutations lead to increased cyclicGMP concentrations in rods. Rod photoreceptors are also particularly susceptible to some mutations in housekeeping genes. Although many more cases of macular degeneration than retinitis pigmentosa occur each year, there is much less known about both genetic and sporadic forms of this disease.
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50
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Reduced cytoplasmic calcium concentration may be both necessary and sufficient for photoreceptor light adaptation. Behav Brain Sci 1995. [DOI: 10.1017/s0140525x00039376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractLight adaptation is modulated almost exclusively by changes in intracellular Ca2+ concentration, and other Ca2+-independent mechanisms are likely to play only a minor role. Changes in Ca2+i may be not only necessary for light adaptation to take place but sufficient to cause it.
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