Structure of V-ATPase from citrus fruit
Bibliographic record
Abstract
Abstract Vacuolar-type ATPases (V-ATPases) are rotary proton pumps involved in numerous essential cellular processes in all eukaryotes. Difficulty in obtaining preparations of purified V-ATPase from plants in sufficient quantities for structural analysis has hindered determining the 3D structure of the plant V-ATPase. We used the Legionella pneumophila effector SidK to affinity-purify the endogenous V-ATPase from lemon fruit. The preparation was sufficient to partially cover an electron microscopy specimen grid, allowing structure determination for the enzyme in two rotational states. The structure defines the ATP:H + ratio of the enzyme, demonstrating that it can establish a maximum ΔpH of ∼3, which is insufficient to maintain the low pH observed in the vacuoles of juice sac cells in lemons and other citrus fruit. Compared to the yeast and mammalian enzymes, the membrane region of the plant V-ATPase lacks subunit f and possesses an unusual configuration of transmembrane α helices. Subunit H, which inhibits ATP hydrolysis in the isolated catalytic region of V-ATPase, adopts two different conformations in the intact complex, hinting at a role in modulating activity in the intact enzyme.
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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 | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".