Nte1p-mediated Deacylation of Phosphatidylcholine Functionally Interacts with Sec14p
Bibliographic record
Abstract
Deciphering the function of the essential yeast Sec14p protein has revealed a regulatory interface between cargo secretion from Golgi and lipid homeostasis. Abrogation of the CDP-choline (CDP-Cho) pathway for phosphatidylcholine (PC) synthesis allows for life in the absence of the otherwise essential Sec14p. Nte1p, the product of open reading frame YML059c, is an integral membrane phospholipase against CDP-Cho-derived PC producing intracellular glycerophosphocholine (GPCho) and free fatty acids. We monitored Nte1p activity through in vivo PC turnover measurements and observed that intracellular GPCho accumulation is decreased in a sec14(ts) strain shifted to 37 degrees C in 10 mm choline (Cho)-containing medium compared with a Sec14p-proficient strain. Overexpression of two Sec14p homologs Sfh2p and Sfh4p in sec14(ts) cells restored secretion and growth at the restrictive temperature but did not restore GPCho accumulation. Instead, newly synthesized PC was degraded by phospholipase D (Spo14p). Similar analysis performed in a sec14Delta background confirmed these observations. These results imply that the ability of Sfh2p and Sfh4p to restore secretion and growth is not through a shared function with Sec14p in the regulation of PC turnover via Nte1p. Furthermore, our analyses revealed a profound alteration of PC metabolism triggered by the absence of Sec14p: Nte1p unresponsiveness, Spo14p activation, and deregulation of Pct1p. Sfh2p- and Sfh4p-overexpressing cells coped with the absence of Sec14p by controlling the rate of phosphocholine formation, limiting the amount of Cho available for this reaction, and actively excreting Cho from the cell. Increased Sfh4p also significantly reduced the uptake of exogenous Cho. Beyond the new PC metabolic control features we ascribe to Sfh2p and Sfh4p we also describe a second role for Sec14p in mediating PC homeostasis. Sec14p acts as a positive regulator of Nte1p-mediated PC deacylation with the functional consequence of increased Nte1p activity increasing the permissive temperature for the growth of sec14(ts) cells.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 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 | 0.001 |
| Research integrity | 0.000 | 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".