Understanding the role of the Vid30c in the nutrient-dependent turnover of hexose transporters in Saccharomyces cerevisiae
Bibliographic record
Abstract
Saccharomyces cerevisiae is confronted with continually changing and diverse nutrient conditions. As such, it has adapted to utilize both a wide variety of nutrient sources and to preferentially use the most nutrient-rich source to obtain a competitive advantage. The transcription, intracellular trafficking and protein turnover of nutrient transporters, including the hexose transporter proteins (Hxts), are strictly regulated in response to nutrient conditions. The low affinity hexose transporter Hxt3p is highly expressed and localizes to the plasma membrane during growth in abundant glucose where it plays a major role in the transport of this sugar. However, following a shift to ethanol as a sole carbon source, Hxt3p is endocytosed and targeted to the vacuole for degradation while its expression is also repressed. In contrast, the high affinity hexose transporter Hxt7p is actively expressed and functional in the plasma membrane when glucose is limiting and nitrogen is abundant. Upon nitrogen starvation or rapamycin treatment, HXT7 transcription decreases and the protein is targeted for degradation. The mechanisms that govern these regulatory steps are poorly understood. The Vid and Gid proteins, several of which compose the Vid30 complex (Vid30c), facilitate the nutrient-dependent degradation of the gluconeogenic enzymes FBPase and Mdh2p when glucose-starved cells are replenished with glucose. Here we show that components of the Vid30c are needed for the ethanol-induced turnover of Hxt3p and the rapamycin or nitrogen starvation-induced degradation of Hxt7p. In addition, we demonstrate that the signals for the ethanol-induced turnover of Hxt3p and the rapamycin-induced turnover of Hxt7p converge on the Vid30c upstream of the Ras/cAMP/PKA pathway, ultimately controlling the degradation of both these hexose transporters. Finally, we provide evidence that the Vid30c controls the localization of the Ras GEF Cdc25p and may therefore directly regulate the activity of the Ras/cAMP/PKA pathway.
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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 | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".