Evidence That the NH2 Terminus of Vph1p, an Integral Subunit of the V0 Sector of the Yeast V-ATPase, Interacts Directly with the Vma1p and Vma13p Subunits of the V1Sector
Bibliographic record
Abstract
The vacuolar-type H(+)-ATPase (V-ATPase) is composed of a peripherally bound (V(1)) and a membrane-associated (V(0)) complex. V(1) ATP hydrolysis is thought to rotate a central stalk, which in turn, is hypothesized to drive V(0) proton translocation. Transduction of torque exerted by the rotating stalk on V(0) requires a fixed structural link (stator) between the complexes to prevent energy loss through futile rotation of V(1) relative to V(0); this work sought to identify stator components. The 95-kDa V-ATPase subunit, Vph1p, has a cytosolic NH(2) terminus (Nt-Vph1p) and a membrane-associated COOH terminus. Two-hybrid assays demonstrated that Nt-Vph1p interacts with the catalytic V(1) subunit, Vma1p. Co-immunoprecipitation of Vma1p with Nt-Vph1p confirmed the interaction. Expression of Nt-Vph1p in a Deltavph1 mutant was necessary to recruit Vma13p to V(1). Vma13p bound to Nt-Vph1p in vitro demonstrating direct interaction. Limited trypsin digests cleaves both Nt-Vph1p and Vma13p. The same tryptic treatment results in a loss of proton translocation while not reducing bafilomycin A(1)-sensitive ATP hydrolysis. Trypsin cleaved Vph1p at arginine 53. Elimination of the tryptic cleavage site by substitution of arginine 53 to serine partially protected vacuolar acidification from trypsin digestion. These results suggest that Vph1p may function as a component of a fixed structural link, or stator, coupling V(1) ATP hydrolysis to V(0) proton translocation.
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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) | 0.002 | 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".