Structure and Function of AChBP, Homologue of the Ligand‐Binding Domain of the Nicotinic Acetylcholine Receptor
Bibliographic record
Abstract
Acetylcholine-binding protein (AChBP) is a novel protein with high similarity to the extracellular domain of the nicotinic acetylcholine receptor. AChBP lacks the transmembrane domains and intracellular loops typical for the nAChRs. AChBP is secreted from glia cells in the central nervous system of the freshwater snail, Lymnaea stagnalis, where it modulates synaptic transmission. AChBP forms homopentamers with pharmacology that resembles the alpha(7)-type of nicotinic receptors. As such, AChBP is a good model for the ligand-binding domain of the nAChRs. In the crystal structure of AChBP at 2.7 A, each protomer has a modified immunoglobulin fold. Almost all residues previously shown to be involved in ligand binding in the nicotinic receptor are found in a pocket at the subunit interface, which is lined with aromatic residues. The AChBP crystal structure explains many of the biochemical studies on the nicotinic acetylcholine receptors. Surprisingly, the interface between protomers is relatively weakly conserved between families in the superfamily of pentameric ligand-gated ion channels. The lack of conservation has implications for the mechanism of gating of the ion channels.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
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".