Introduction of Session 8, “Structural mechanism of animal rhodopsins and GPCR”
Bibliographic record
Abstract
G protein-coupled receptors (GPCRs), seven helical transmembrane proteins, are responsible for signal transduction pathways by detecting diffusible signaling molecules such as hormones, neurotransmitters and odorants.Animal rhodopsins are highly specialized photoreceptor GPCRs for vision and function via isomerization by the light absorption of retinal chromophore (as a signaling molecule).The dynamic structural information of rhodopsin and GPCRs has recently been elucidated through several types of spectroscopies and structural analyses.In the session 8 chaired by me and Dr. Gebhard F. X. Schertler from Paul Scherrer Institute, five researchers presented cutting-edge results regarding 'structural mechanism of rhodopsins and GPCRs', as described below.The first speaker was Dr. Hideaki Kato from the University of Tokyo, who discussed the 'structural and functional diversity in pump-like cation channelrhodopsins'.To optically control cell excitability, optogenetics has revolutionized neuroscience.To broaden the application of optogenetics, increasing numbers of ion-translocating rhodopsins (ion pumptype rhodopsins and ion channel-type rhodopsins) have been engineered or discovered in nature.Recently, a new type of channelrhodopsins, pump-like cation-conducting channelrhodopsins or bacteriorhodopsin-like channelrhodopsins (PLCRs or BCCRs), have been discovered and attracted broad attention due to their unique properties (e.g., large photocurrents, high light sensitivity, high ion selectivity).In his talk, he presented the cryo-EM structures of PLCRs [1] and discussed their structure-function relationships.The next speaker was Dr. Oliver P. Ernst from University of Toronto, who discussed 'activation studies of opsin and adenosine A2a receptor'.In his talk, he presented studies on the activation of the apoprotein opsin by odorants.Three crystal structures of the active conformation of opsin, Ops*, with monoterpene odorants in the orthosteric retinal binding pocket, as well as biochemical, biophysical and electron paramagnetic resonance (EPR) [2] studies reveal how these odorants can act as agonists to promote conformational changes towards Ops*.He also presented the conformational equilibrium of adenosine A2a receptor.The third speaker was Dr. Xavier Deupi from Paul Scherrer Institute, who talked about 'structure and activation of lightactivated G protein-coupled receptors'.A wealth of biophysical, functional, and structural data have made the mammalian visual low-light receptor rhodopsin a paradigm of the GPCR family.Recently, they discovered that such similarities are not limited to vertebrate rhodopsins but extend even to visual receptors from invertebrates [3].In his talk, he presented (i) a novel position for the retinal counterion in the non-bistable box jellyfish rhodopsin that is discovered by employing computational structural models validated by mutagenesis and activity assays, and (ii) the structure of an early active intermediate of bovine rhodopsin (obtained at the SwissFEL free-electron laser) suggesting that the earliest structural rearrangements upon activation already appear in regions involved in later stages of the conserved class A GPCR activation mechanism.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.003 |
| Meta-epidemiology (narrow) | 0.002 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.002 | 0.004 |
| Research integrity | 0.004 | 0.004 |
| Insufficient payload (model declined to judge) | 0.186 | 0.103 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".