Rhodopsin serves as a model GPCR whose structures and spectroscopic behavior are used to study activation mechanisms. The review emphasizes comparisons across inactive, intermediate, and active states.
First-pass extracted concept
rhodopsin
Candidate: concept label2 source documents9 linked claims
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Aliases
visual pigment rhodopsin
Extracted Explainers
What the tool is doing
Resources required
Use of rhodopsin in this review depends on structural and spectroscopy datasets, including crystal structures and related biophysical analyses.
Its function depends on the chromophore 11-cis-retinal covalently bound to opsin and on photon absorption to trigger isomerization.
What problem it solves
What it does not solve
Alternatives
The review contrasts rhodopsin with the broader set of currently available GPCR structures, including agonist-bound GPCR structures used for comparison.
The review places rhodopsin in the context of other GPCR structures, but the abstract does not name specific alternative receptor tools.
Evidence Snippets
Rhodopsin ... is both a retinal-binding protein and a G protein-coupled receptor (GPCR) ... a model system for the important family of Class A (also referred to as "rhodopsin-like") GPCRs.
Many biochemical and both low- and high-resolution structural approaches have been utilized to increase our understanding of rhodopsin, the key molecule of this signaling cascade.
Supporting Sources
Linked Claims
Comparing inactive, intermediate, and active rhodopsin transmembrane-domain structures can reveal early conformational changes during ligand-induced GPCR activation.
Rhodopsin is likely to play an important role in applying X-ray free electron laser crystallography to time-resolved structural biology in membrane proteins.
Rhodopsin remains a relevant model system for studying the molecular mechanisms of GPCR activation.
Analysis of a conserved ligand-activated transmission switch in the context of the rhodopsin activation cycle suggests that many agonist-bound GPCR structures may correspond to intermediate active states.
Analysis of the third intracellular loop in rhodopsin structures provides insight into structural and dynamic properties of a region that is absent in many currently available GPCR structures.
Activated rhodopsin enables activation of the heterotrimeric G protein transducin by triggering nucleotide exchange.
Quoted textsource-backed
This state allows it to activate the heterotrimeric G protein, transducin, by triggering nucleotide exchange.
Rhodopsin contains 11-cis-retinal covalently bound to opsin, and photon absorption isomerizes the chromophore to an all-trans-retinylidene conformation that drives receptor activation.
Quoted textsource-backed
Rhodopsin, a member of the GPCR or seven-transmembrane spanning receptor superfamily, is composed of a chromophore, 11-cis-retinal that is covalently bound by a protonated Schiff base linkage to the apo-protein opsin at Lys(296) (in bovine opsin). Upon absorption of a photon, isomerization of the chromophore to an all-trans-retinylidene conformation induces changes in the rhodopsin structure, ultimately converting it from an inactive to an activated state.
Understanding rhodopsin structure and function requires critical examination of crystal structures from different photointermediate states.
Quoted textsource-backed
To fully understand the structural and functional aspects of rhodopsin it is necessary to critically examine crystal structures of its different photointermediates.
Phototransduction is presented as a well understood model system for GPCR signaling.
Quoted textsource-backed
The phototransduction cascade is perhaps the best understood model system for G protein-coupled receptor (GPCR) signaling.