G Proteins and Phototransduction
Annual Review of PhysiologyPublished 1 March 2002
Vadim Y. Arshavsky, Trevor D. Lamb, Edward N. Pugh
Citations657
SJR quartileQ1
SJR score7.82
SNIP4.62
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TL;DR
How the interplay between the mechanisms that contribute to amplification and those that govern termination of G protein activity determine the speed and the sensitivity of the cellular response to light is examined.
Abstract
Phototransduction is the process by which a photon of light captured by a molecule of visual pigment generates an electrical response in a photoreceptor cell. Vertebrate rod phototransduction is one of the best-studied G protein signaling pathways. In this pathway the photoreceptor-specific G protein, transducin, mediates between the visual pigment, rhodopsin, and the effector enzyme, cGMP phosphodiesterase. This review focuses on two quantitative features of G protein signaling in phototransduction: signal amplification and response timing. We examine how the interplay between the mechanisms that contribute to amplification and those that govern termination of G protein activity determine the speed and the sensitivity of the cellular response to light.
Keywords
NeuroscienceBiochemistry, Genetics and Molecular Biology
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Journal of Biological ChemistryModules in the Photoreceptor RGS9-1·Gβ5L GTPase-accelerating Protein Complex Control Effector Coupling, GTPase Acceleration, Protein Folding, and Stability
83 Citations2000Wei He, Lisha Lu +7 more
Within the GAP complex organized around the RGS domain of RGS9-1, a functional role is identified for the Gγ-like-Gβ 5L complex in regulation of GAP activity by an effector subunit, cGMP phosphodiesterase γ and in protein folding and stability of R GS9- 1.
ScienceFacilitation of Signal Onset and Termination by Adenylyl Cyclase
83 Citations1999Klaus Scholich, Jason B. Mullenix +6 more
It is demonstrated that adenylyl cyclase functions as a GTPase activating protein (GAP) for the monomeric Gsalpha and enhances the GTP/GDP exchange factor (GEF) activity of receptors.
Current Opinion in NeurobiologyActivation and inactivation steps in the visual transduction pathway
81 Citations1997Krzysztof Palczewski, John C. Saari
Studies examining the molecular defects that cause delayed dark adaptation suggest that the desensitizing substance is recognized by rhodopsin kinase and/or arrestin and, therefore, is probably a complex comprising all-trans-retinal and opsin.
Proceedings of the National Academy of SciencesA regulator of G protein signaling interaction surface linked to effector specificity
81 Citations2000Mathew E. Sowa, Wei He +2 more
A cluster of residues in the R GS domain that includes the RGS-G(alpha) binding interface and extends to include additional functionally important residues on the surface, which likely form a general site for regulation of G protein-coupled signaling cascades, possibly by means of effector interactions.
BiochemistryInteraction between the retinal cyclic GMP phosphodiesterase inhibitor and transducin. Kinetics and affinity studies
80 Citations1993Annie Otto‐Bruc, Bruno Antonny +3 more
The kinetics and affinity of the interaction between PDE gamma and T alpha GDP or T alpha GTP gamma S were determined by monitoring changes in the proteins' tryptophan fluorescence.
BiochemistryGTP hydrolysis by purified .alpha.-subunit of transducin and its complex with the cyclic GMP phosphodiesterase inhibitor
78 Citations1993Bruno Antonny, Annie Otto‐Bruc +2 more
The single-turn GTP hydrolysis by isolated and soluble trans Ducin has been time-resolved using a rapid flow filtration technique which takes advantage of the GTP-requiring detachment of transducin alpha-subunits (T alpha) from photoactivated rhodopsin.
Journal of NeuroscienceCopurification of Brain G-Protein β5 with RGS6 and RGS7
77 Citations2000Jianhua Zhang, William F. Simonds
It is suggested that a large fraction of membrane-targeted Gbeta5 has no associated G subunit and therefore functions outside the canonical framework of G(beta)(gamma) interactions.
Journal of Biological ChemistryTransducin activation in electropermeabilized frog rod outer segments is highly amplified, and a portion equivalent to phosphodiesterase remains membrane-bound.
75 Citations1990Mark P. Gray-Keller, Michael Biernbaum +1 more
An electropermeabilized preparation of frog retinal rod outer segments (ROS) has been developed to examine the light sensitivity and amplification of visual transduction reactions in a minimally disturbed environment and a specificity for light-induced GTP versus GDP binding is observed.
Current Opinion in NeurobiologySome unresolved issues in the physiology and biochemistry of phototransduction
74 Citations1992Peter B. Detwiler, Mark P. Gray-Keller
The purpose of the present review is to dispell the popular, but false, impression that visual transduction is understood fully by focusing on some of the unresolved issues.
Journal of Biological ChemistryThe α-Helical Domain of Gαt Determines Specific Interaction with Regulator of G Protein Signaling 9
71 Citations1999Nikolai P. Skiba, Chii‐Shen Yang +3 more
A distinct, nonoverlapping pattern of RGS and Pgamma interaction with Galphat suggests a unique mechanism of effector-mediated GAP function of the RGS9.
FEBS LettersSub‐second turnover of transducin GTPase in bovine rod outer segments A light scattering study
69 Citations1988Rafael Wagner, Nicholas J. P. Ryba +1 more
A fast, regenerative light scattering signal from bovine ROS, the PA‐signal, reflects the light‐induced, transient activation of transducin, indicating that rhodopsin deactivation and not GTPase activity is rate limiting in the authors' in vitro system.
FEBS LettersTransducin GTPase provides for rapid quenching of the cGMP cascade in rod outer segments
69 Citations1989Vadim Y. Arshavsky, Marina P. Antoch +2 more
The results obtained allow the conclusion that phosphodiesterase quenching coincides with transducin‐bound GTP hydrolysis independently of ROS concentration, which is sufficiently high for satisfying the real rate of photoresponse reversion in dark‐adapted rods.
Journal of Biological ChemistryThe Effector Enzyme Regulates the Duration of G Protein Signaling in Vertebrate Photoreceptors by Increasing the Affinity between Transducin and RGS Protein
68 Citations2000Nikolai P. Skiba, Johnathan A. Hopp +1 more
The mechanism by which PDEγ regulates the rate of transducin GTPase is addressed, and data indicate that a single RGS9·Gβ5L molecule is capable of accelerating the GTP enzyme activity of ∼100 trans Ducin molecules/s, which is faster than the rates reported previously for any RGS protein and is sufficient for timely photoreceptor recovery in both rod and cone photoreceptors.
Journal of Biological ChemistryAn Effector Site That Stimulates G-protein GTPase in Photoreceptors
67 Citations1995Vladlen Z. Slepak, Nikolai O. Artemyev +7 more
Observations suggest that the role of PDEγ in activation of the transducin GTPase rate may be based on multiple hydrophobic interactions between these molecules.
Trends in NeurosciencesWatching G proteins at work
64 Citations1990Rainer Uhl, Rafael Wagner +1 more
Using the technique of light-scattering, it can be shown that certain properties of the coupling between transducin and rhodopsin are different in a structurally well-preserved system as compared with rod material used for conventional biochemical studies.
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