Discovery of an allosteric binding site for anthraquinones at the human P2X4 receptor
Bibliographic record
Abstract
P2X receptors are trimeric ATP-gated ion channels. The P2X4 receptor subtype is a promising drug target for the treatment of inflammatory diseases, neuropathic pain, and cancer. Here, the water-soluble anthraquinone derivative Cibacron Blue, previously described as a P2X4 receptor modulator, is selected as a lead structure, and structure-activity relationships are investigated. A chimeric receptor approach, combined with mutagenesis and docking studies, is applied to identify the allosteric binding site and the interacting amino acid residues. We discover that Glu307, located in the upper body of the receptor, is prone to form an intermolecular "ionic lock" with basic amino acid residues, thereby preventing high-affinity binding of anthraquinone derivatives. Exchange of Glu307 for threonine leads to a dramatic potency increase for anthraquinones in blocking P2X4 receptor function. The structure of the human P2X4-E307T receptor in complex with the anthraquinone derivative PSB-0704 is determined by cryo-electron microscopy at a resolution of 3.35 Å. This reveals an allosteric binding site in the upper body at the interface of the receptor trimer subunits, which differs from previously described allosteric sites on P2X receptors. Our results provide a rational basis for structure-based drug design towards potent and selective P2X4 receptor antagonists.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".