Regulation of Yeast Glycerol‐3‐Phosphate Acyltransferase Gpt2p/Gat1p Through Phosphorylation
Bibliographic record
Abstract
Glycerol‐3‐phosphate acyltransferases (GPAT) catalyze the acylation of glycerol‐3‐phosphate, the first and rate limiting reaction in de novo synthesis of phosphatidic acid (PA). GPAT redundancy led to the hypothesis that isoenzymes are forming different PA pools which supply different pathways. In the model organism S. cerevisiae two GPATs have been identified, Gpt2 and Sct1. Most recently we demonstrated the important role of Gpt2 (but not Sct1) in cells challenged by oleic acid as the only carbon source. Whereas growth in oleic acid normally induces lipid particle accumulation, cells lacking GPT2 failed to accumulate these neutral lipids storage compartments, exhibited a strong growth defect, and cell viability was reduced. The fact that the intracellular distribution of Gpt2 and its phosphorylation status changed under this growth condition attracted our interest. We have identified 3 highly conserved phosphorylation sites in Gpt2 by mass spectrometry, localized to a Ser rich region in the carboxy‐end. Ser to Ala triple mutations as well as deletion of the Ser rich region, were introduced in the yeast genome to investigate the role of phosphorylation in the regulation of Gpt2. Importantly, both Gpt2 mutant forms retain enzymatic activity sufficient to support life of cells lacking Sct1. Microscopic inspection of phosphomutants revealed changes in lipid droplet formation. In line, cells overproducing these mutants exacerbated this phenotype, suggesting that lack of Gpt2 phosphorylation leads to abnormal accumulation of lipid droplets and carbon source consumption. The role of the Gpt2 serine‐rich carboxy‐end in mediating protein‐protein interactions is currently investigated
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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) | 0.000 | 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".